Celtreos
Library artwork
| Developer: | Kevin Grant |
|---|---|
| Music: | Kevin Grant |
| Program: | Kevin Grant |
| Art: | Kevin Grant |
| Release date: | 2017 |
| Next game: | None |
Celtreos (セルトレオス) is a 2D horizontal scrolling space-themed game created by Kevin Grant in 2017 (with continuous updates through 2024). It is available for macOS on Steam, and iOS and tvOS on the App Store. It supports one or two local players simultaneously.
Everything in the game is unlocked at the beginning; it is possible to start the game at any stage but all stages must be played in a sequence to see the game ending.
This game is notable for not only having power-ups but also power-down orbs (penalties), which temporarily inconvenience the player in various ways. These include: preventing scoring, reducing weapon power, reducing weapon range, slowing weapons down, preventing weapon switching altogether, or even eliminating weapons from your arsenal.
It is also possible to play this game on very large displays with good quality due to vector graphics.
Contents
Gameplay Overview
Celtreos supports one or two players simultaneously, with 7 playable ships and 13 stages. Each stage ends with a boss fight, and the final stage has two very long boss fights.
There is a power-up system, a large number of weapons and defenses (including special abilities that consume charges), a variety of different playable ships, and the ability to slow down.
Soundtrack
The game has a massive 30-song soundtrack, over 45 minutes of music. The main options screen allows any song to be played, and the same options are available in-game. It is also possible to adjust the volume or turn off the sound.
Celtreos has the ability to interface with the music player from the OS (any app on iOS, or iTunes/Music on macOS). If these apps are playing music instead, the game exposes an option to auto-next-song for key game events (new stages or boss fights), allowing players to craft their own favorite soundtracks to suit the gameplay.
Controls
Celtreos supports a variety of different inputs: keyboard, mouse or trackpad (may be combined with keyboard or used separately), game controllers (MFi, Xbox, DualShock or DualSense), and touch controls on iOS. There is no way to remap the key or button assignments.
The ship fires weapons continuously.
Keyboard
- W/A/S/D or arrow keys: Move up/left/down/right
- Q: Rotate between available weapons
- B or Touch Bar: Use special ability
- Caps Lock: Toggle default speed
- R: Switch back to most-recently-used weapon
- 1 or Touch Bar: Switch directly to default weapon
- 2 or Touch Bar: Switch directly to multiway-class weapon (if any)
- 3 or Touch Bar: Switch directly to sideways-class weapon (if any)
- 4 or Touch Bar: Switch directly to locator-class weapon (if any)
- 5 or Touch Bar: Switch directly to destroyer-class weapon (if any)
- 6 or Touch Bar: Switch directly to movement-opposing-class weapon (if any)
Mouse
- Move mouse: Move in any direction
- Left button (Press) + ⌘: Dash straight toward location
- Left button (Hold): Temporarily switch speed while button is held
- Right button: Rotate between available weapons
- Double-click: Use special ability
- 3rd button: Use special ability
Game Controller
- A-button or DualSense X-button (Hold): Temporarily switch speed while button is held
- B-button or DualSense circle-button (Press): Use special ability
- X-button or DualSense square-button (Press): Toggle default speed
- Y-button or DualSense triangle-button (Press): Switch back to most-recently-used weapon
- L1/R1: Rotate between available weapons
Touch Screen
- Drag with finger on screen: Move in any direction
- Tap elsewhere on screen: Dash straight toward location
- Other abilities have onscreen controls
Unlockable Secrets
There are a number of “Achievements” that can be scored in the game. Unless you have enabled Hard Difficulty, scoring an Achievement also makes your player invincible for several seconds with the ability to float through walls!
The conditions to discover each Achievement are secret but they range from almost unavoidable (like scoring a certain number of points) to somewhat difficult (there is one that requires you to obtain a certain number of special-ability charges, which can only be done if you go through much of the game without ever using special abilities).
There are currently at least 15 ways to score an Achievement.
Although Achievements can be scored in each play-through, the game has a “trophy room” (accessible from the main options screen) to track unique Achievements that have been found over time, as well as other completion goals in the game. A “Hints” option can help to figure out what the others may be.
Ships
There are 7 ships available. The differences are mostly cosmetic, except that larger ships will be harder to navigate safely in tight spots and weapons with more than one starting point (such as “Phaser”) will be anchored differently on each ship design.
- Flyer of Fire, Mark II
- Armaton
- Mini
- Elwing
- Jade Piercer
- Beryl Blade
- Verdigris Viper
Weapons and Defenses
In Celtreos, abilities are gathered into weapon arrays and you can customize all of them in the options screen at the start of the game. In a given stage, you have just one default weapon and rely on power-ups to gather more (and you can lose them if you die, unless you set a preference in the game to prevent this, obtain a Preserver power-up, or are using a weapon slot that has attained the Preserver II ability).
At the end of every boss fight, one to three alternate weapon arrays spawn, giving you the opportunity to swap out your abilities if you want to.
The “Gun Mount” preference setting can be used to influence initial weapon firing patterns, especially when combined with multipliers (“×2” or “×3”). These can be changed during the game by special power-ups.
Each weapon array has slots that categorize behavior, and (see “Controls” above) each type can be accessed directly from the keyboard as long as you have acquired the right power-up. Weapon slots can be improved over time by accumulating EXP points; see “EXP” below.
Note: There is a guide to Celtreos Weapons on Steam (see “References & Contributors” below).
There is a special ability in each array:
- Bomb: Damage covering a large area on the screen
- Lightning: Heavy damage in a cone behind the ship
- Ray Burst: Rapid enemy-seeking lasers for several seconds
- Time Warp: Not an attack but a way to slow down enemies on the screen for several seconds
- Concentrator: Extensive damage covering a narrow area in front of the ship
In addition, each array has one type of protection:
- Shield: Worn down when damaged
- Deflector: Bounces attacks in new directions (an interesting defense in two-player games)
- Armor: Regenerating plates that also have a melee attack
- Barrier: A mixture of deflection and attack
- Bumper: Reduces chance of collision with walls and other obstacles
The array also determines the type of defenders that can be acquired, up to 5 at once; these occupy different positions on the screen and aid your main ship:
- Defender: Orbs that rotate around your ship, damaging anything they touch
- Shadow: After-images that provide additional forward cover fire
- Trailer: After-images that provide additional backward cover fire
- Sentry: Flying drones that shoot lasers at nearby foes
- Prism: Fields that can drastically alter weapon trajectory
EXP
EXP is awarded over time as weapons in a particular slot are used. The weapon display shows both accumulated EXP (aligned with accumulated tiers) as well as pending EXP (that can potentially lead to weapon updates at the start of a future stage).
At the start of each new stage, any weapon slots with enough EXP to reach a new tier will change tiers (after score bonuses are awarded). EXP is not on a linear scale so it is harder to reach higher tiers than lower tiers.
The possible weapon updates are as follows:
| Class | Tier 1 | Tier 2 | Tier 3 | Tier 4 | Tier 5 |
|---|---|---|---|---|---|
| Default | None | None | Resilience | Expand | ??? |
| Multi-Way | +10000 | Preserver II | Waves | Rapid Fire | ??? |
| Sideways | +10000 | Preserver II | Rapid Fire | Expand | ??? |
| Locator | +10000 | Preserver II | Range Up | Smart-Target | ??? |
| Destroyer | +10000 | Preserver II | Weaken | Enlarge | ??? |
| Opposer | +10000 | Preserver II | Power Up | Always-On | ??? |
More on the weapon slot abilities shown above:
- +10000: Score bonus of 10000 points
- Always-On: Weapon is now constantly available, firing alongside any currently-selected weapon
- Enlarge: Projectiles are bigger
- Expand: Projectiles cover a wider area in one dimension
- Power Up: Projectiles do more damage
- Preserver II: The “×” orb can’t destroy this weapon, and it is not lost after player death
- Range Up: Locator-class weapons can see targets from further away
- Rapid Fire: Faster by default, yet still further increased by the “Rapid Fire” power-up
- Resilience: Default-class weapons cannot be reduced below power level 3
- Smart-Target: Locator-class weapons ignore invulnerable projectiles
- Waves: Weapons fire is periodically interspersed with larger projectiles
- Weaken: Weapon is less powerful than before!
Items
Items are both good and bad; they can spawn randomly, float in the game world, or show up after destroying small power-up ships. Weapon arrays will only spawn at the end of a stage, immediately after the boss fight ends.
If a power-up is obtained, the game speaks the name of the new weapon! (The volume of these vocals can be configured separately from other sound effects, as well.)
Good Items
| Power-Up | Effect |
|---|---|
| “1UP” | Extra life (you also gain an extra life every 250,000 points); does not spawn when Hard Difficulty is enabled |
| Bomb/Lightning/Ray Burst/Time Warp/Concentrator | Extra charge (special ability use) of this type; varies based on current weapon array |
| “➕” | Increase power of main weapon and auto-switch to main weapon; you can also stay alive awhile and your main weapon will gradually power-up by itself |
| New weapon | Obtain new weapon (varies) and switch to it automatically, though you can switch back to any other weapon you have |
| Shield/Deflector/Armor/Barrier/Bumper | Protect your ship (varies based on current weapon array); rarely spawns when Hard Difficulty is enabled |
| Defender/Shadow/Trailer/Sentry/Prism | Obtain additional defender (varies based on current weapon array; you can gain up to 5) |
| “500”/“2500”/“10000” | Score bonus |
| “⭐︎” Preserver | Current weapon is not lost when you die; or, if currently using the main weapon, its maximum power is saved instead of being reset to minimum; note that this does not spawn if the “Keep weapons after death” game setting is in effect |
| “△” Rapid Fire | Weapons fire much faster for several seconds |
| “×2” Twin Fire | Current weapon is doubled, firing from two locations for several seconds (overrides any active “×3”) |
| “×3” Triple Fire | Current weapon is tripled, firing from THREE locations for a few seconds (overrides any active “×2”) |
| “EXP×2” Double EXP | Weapon EXP accumulates more quickly for several seconds |
| “❔” Fragment | Gold fragment orbs are worth nothing by themselves; exactly three spawn in every stage, and you must find all of them to receive a cluster of power-ups as a bonus |
| Weapon Mount | Specifies the locations on your ship where weapons start firing; some of these will move, and they also change behavior when multipliers are active |
| Weapon Array | Up to three of these will spawn at the very end of the stage, after the boss fight ends; you can swap out all of your abilities this way (or ignore them and keep what you have) |
Bad Items
| Power-Down | Effect |
|---|---|
| “➖” | Substantially decrease power of main weapon and auto-switch to main weapon |
| “▽” Slow Fire | Weapons fire much slower for several seconds |
| “✖️” Kill Weapon | Current weapon is destroyed and cannot be used unless you find the power-up for it again; in addition, main weapon power is reduced to minimum; note that weapon slots that have attained the “Preserver II” ability are immune to this effect |
| “🔒” Lock Weapons | Current weapon cannot be changed for several seconds (or until you die); switching function is temporarily unavailable |
| Reduced Range | All weapons have a drastically reduced firing distance |
| “0” Zero Score | No scoring for several seconds |
Player Death
Most enemy attacks will kill the player instantly unless a defense is active (for example, “Shield” might absorb the entire attack and become weaker but the player is saved). The player’s ship is also destroyed immediately by hitting walls, as well as most boss ships, and only a “Bumper” will save the player from these collisions.
At time of death, all weapons and defenses are lost (unless the “Keep weapons after death” game setting is in effect, or a “Preserver” is in effect; see “Items”), and the main weapon’s power is reduced to minimum. The number of “charges” left for special abilities is not reset.
When the player dies, there is a chance that power-ups will spawn. These may include most of the weapons and other abilities that the player had, or a single very useful item (like “1UP” or “Rapid Fire”). It is also possible that nothing will happen.
The number of lives left is only displayed on the screen at time of death.
Lives can be configured from 1-9 at the beginning of the game. They can be gained in-game with the “1UP” power-up (see “Items”), and also every 250,000 points (see “Scoring”). In two-player games, each player has a separate Lives counter.
There are no “continues” in Celtreos; once all lives are lost the game is over. The “GAME OVER” display remains on screen until dismissed, and the current stage continues to scroll and enemies still appear (including the boss at the end). Thus, you can see a preview all the way to the end of an unfamiliar stage by waiting at the Game Over screen. Power-ups do not appear in Game Over mode so you will still not know where those would have spawned.
Observable Screen & Playing Field
Most stages are two “screens” high, where the player can move toward the top or bottom edges of the screen to gradually scroll and reveal a different area. In two-player games, both ships must be near the top or bottom to trigger scrolling.
Some stages will periodically rotate the entire play field, causing enemies and power-ups to come from unusual directions.
Scoring
Scoring is primarily useful for gaining new lives every 250,000 points, and Achievements (though many Achievements are not based on score).
Three of the power-ups in the game can boost score (by 500 points, 2500 points or 10000 points) and they are generally placed in optional areas that may be tricky to reach.
At the end of every stage there is a time bonus for finishing relatively quickly, and a shooting bonus for destroying lots of enemies. This is also the time that weapons change tiers based on accumulated EXP.
| Time Bonus | Requirement |
|---|---|
| 0 | - |
| 5000 | Finish no more than 60 seconds over current stage’s target time |
| 10000 | Finish no more than 30 seconds over current stage’s target time |
| 25000 | Finish no more than 10 seconds over current stage’s target time |
| 50000 | Beat current stage’s target time by at least 10 seconds |
| Shooting Bonus | Requirement |
|---|---|
| 0 | - |
| 5000 | Shoot >70% of spawned enemies |
| 10000 | Shoot >80% of spawned enemies |
| 25000 | Shoot >85% of spawned enemies |
| 50000 | Shoot >92% of spawned enemies |
Strategy
Normal Difficulty / General
- Boss fights will be easier if you find vulnerable spots such as turrets and destroy those first, even if they do not count toward the boss’ total health. Also, do not waste time; some bosses will regenerate a shield after a while!
- At the end of every boss fight, one to three alternative weapon arrays will always spawn. You do not have to change out your weapons but once you become familiar with each stage you may find that certain abilities will work better than others in a given stage.
- Learning the exact conditions for an Achievement, and then timing it, can be very helpful to make progress in the game. For example, if you are nearing a boss fight and close to a key score, holding off on shooting a few enemies may help you to time the Achievement during a difficult phase of the boss, and gain crucial seconds of invincibility!
- Every stage has exactly 3 gold “Fragments” that are worthless unless you get all 3 of them. Learning where these can be is very useful because they will cause many useful power-ups to spawn (although the exact set is random). In some stages a Fragment may randomly spawn in one of exactly two places instead of always being in the same place.
- Some power-downs may be classified as “bad” but they can factor in to your strategy. For instance, picking up a “🔒” Lock Weapons orb at just the right time can help you power through a screen full of enemies, if you want to make sure your weapon isn’t auto-switched to anything else that might be floating by.
- There are a lot of different weapon combinations to experiment with! Default weapons are not only attacks by themselves, they modify some other weapons; for instance, the attacks used by defenders like “Shadow” and “Trailer”, and the secondary attacks of certain weapons such as “Sideliner”. Also, weapon mounts significantly change the spread of weapons fire, especially with multipliers.
- The “Prism” defender pod drastically alters the trajectory of many weapons, to the point where they are almost entirely different weapons; experiment with these to find new methods of attack.
- Some environments (such as space) change weapon behavior! For example, a weapon that naturally relies on gravity like “Ground Wave” will actually float in space, producing an entirely different attack pattern. Try it!
- Ship speed can be changed in multiple ways and this can be crucial for navigating tight areas.
Hard Difficulty
- Extra lives are extremely difficult to obtain in Hard Difficulty mode. The only way to get them is through scoring (every 250,000 points) so be thorough and fast to maximize your bonuses!
- Many bullets are invulnerable, and even the vulnerable ones are harder to destroy in this mode. Deflector and Barrier are quite useful, although they are less likely to spawn.
- In some situations the abilities that consume Charges will absorb onscreen bullets. The cooldown is much greater however so don’t use them until you really need to!
Story
The game is set far in the future, when there is widespread colonization of space. This peaceful society did not prioritize having strong defenses. When unknown enemies suddenly appeared and launched vicious attacks, there were few options and time was running out. In a city far from combat, scientists experimenting with new sources of energy found something that could be rapidly repurposed for combat, using devices small enough to fit aboard a few jets parked at the facility. You now pilot one of these ships, and fight for survival.
(To see the game ending story, all stages must be completed in one run; while you can start at any stage, the game will loop back to the beginning until the rest are completed.)
Version Differences
The touchscreen versions of the game (iPhone/iPad) have onscreen controls, whereas on macOS/desktop and tvOS most information is only displayed as needed. The graphics quality is also much higher on the macOS and tvOS versions, more suited to large displays.
Trivia
The game logo on the options screen can be used to view the game introduction (and story) at any time.
Gallery
See Celtreos/Gallery for our collection of images and scans for the game.
Video References
Trailers of the game can be found on Steam and YouTube.
References & Contributors
- This page was created by the developer of this game, Kevin Grant.
- Additional information on game weapons and power-ups: Celtreos Guides (on Steam).
- General: Celtreos Help
- Short videos: Celtreos YouTube Channel
