Story takes place in the year 21XX, where a mysterious alien force known as "Purple Erosion" has taken over Earth's Moon, using it as their lunar base of operations as they orchestrate their plans of taking over the Earth. Piloting one of the most advanced space fighters around, it's up to you (and a friend) to stop their invasion on Earth, take them on through outer space, and reclaim the Moon from Purple Erosion to stop them once and for all. How, you may ask? By shooting down everything Purple Erosion throws at you!
Like in Judgement Silversword, the game is split into a few dozen areas, with a Boss Battle every several areas, and the player pilots a ship with a Spread Shot, a narrow shot, and a shield. New to this game are the presence of multiple gameplay modes:
- Original, in which the player has constant shot power and tries to kill waves of enemies as fast as possible without letting any escape to rack up points.
- Advanced, which uses the power-up system (the player ship starts with weaker weapons than Original, but eventually gets more firepower than in Original), has more lenient penalties for missing enemies, and introduces purple pyramid point items that spawn whenever bullets are cancelled or blocked.
- Time Attack, in which the player tries to complete the game as fast as possible, within the time limit. Time extends when going to a new area. The player has unlimited lives, but dying will take 5 seconds off of the time limit. At the end of the game, the player's remaining time is subtracted from the clear time.
Although the game was Japan-only, it is region-free, so the game can be played on any Xbox 360 regardless of its region code. The game was also bundled with Judgement Silversword and its gaiden game Cardinal Sins, giving players the ability to play its WonderSwan Color spiritual ancestors on a home console. In 2012, Qute released the arrange soundtrack for use with the game in the form of DLC. Another spiritual successor, Ginga Force, was released in February 14th, 2013, followed by a Compilation Re-release four months later bundled with ESCHATOS and the games' soundtrack. A PC version of ESCHATOS was published by Degica and released through Steam overseas on September 18, 2015 along with a port of Judgement Silversword, and the arranged soundtrack DLC as well on November 13, 2015.
ESCHATOS contains examples of:
- Like in Judgement Silversword, these tend to come at a mildly generous pace.
- In Time Attack, 1-ups will restore your time limit by 15 seconds.
- 2½D: The game uses 3D graphics, but the gameplay is mostly played through a 2D plane, including segments where the camera goes for an overhead rail-shooter perspective. An optional toggle will show the altitude of enemies relative to your position.
- Bullet Hell: ESCHATOS, as well as its spiritual predecessors and successor, will unleash a hailstorm of red bullets all over the screen.
- Compilation Re-release: The Ginga Force & ESCHATOS Wonder Pack, bundling ESCHATOS and Ginga Force along a soundtrack with music from both games.
- Death Is a Slap on the Wrist: In Time Attack, you get unlimited lives, and dying subtracts 5 seconds plus whatever time is lost waiting to respawn. You'll still get a game over if you die too much, but compared to the finite-lives modes, it's easier to finish the game on one credit (and in fact, Time Attack only permits a single credit).
- Drought Level of Doom: The game is usually fairly generous with 1-ups, but Stage 3 (Areas 12-15) has no 1-ups at all.
- Embedded Precursor: The Xbox 360 version includes enhanced color versions of Judgement Silversword and Cardinal Sins in the game. On PC however, the WonderSwan predecessors are sold separately.
- A much more subtler version of this trope, bordering on Shout-Out, come in the form of of Wonder Witches, secret items you can collect whose point value are based off of your multiplier, much like DonPachi's bee items. The Wonder Witch, in real life, is a WonderSwan homebrew development kit which was used to make Judgement Silversword and Cardinal Sins in the early 2000s.
- Endless Game: Original and Advanced have the "Endless" difficulty, which starts off at the equivalent of Easy and progresses up the difficulty tiers each time you finish one playthrough.
- Excuse Plot: Aliens from outer space took over the Moon and plans to invade Earth. Pilot your space fighter and kick some ass.
- Hard Mode Perks: Your maximum score multiplier increases with higher difficulties. The max multiplier is x10 on Easy, x20 on Normal, x50 on Hard, and on Hardest there is no maximum multiplier.
- Harder Than Hard: Hardest difficulty, which is so hard that on the Xbox Live leaderboards, only one player in Original Mode and one player in Advanced have cleared it. However, M-KAI has stated in an interview that the game is designed with Hard mode as the "main" difficulty in mind, arguably subverting this trope.
- Level in Boss Clothing: Stage 3 (Areas 12 through 15) is spent fighting against a space station, and you deplete its health over the course of the stage. The boss music doesn't play until the final area, when it's lost two of its three health bars.
- Magikarp Power: In Advanced Mode, your ship starts off with weaker weaponry than in Original and Time Attack, but at maximum power, it is significantly more powerful than its non-Advanced counterpart.
- Nerf: The Spread Shot from Judgement Silversword was further nerfed (in Cardinal Sins, its range was reduced) by giving it no direct-forward coverage except at level 1 and giving it even lesser range unless it's at full power in Advanced mode.
- Power-Up: In Advanced Mode. Obviously, it makes your shots stronger; in addition to that it raises your multiplier. However, your shield capacity decreases as you gain more power-ups.
- Retraux: The soundtrack is done in FM synth by Yousuke Yasui, a game music composer well-known for making retro-style game music. The graphics also give off a very Sega NAOMI look and feel to it
- Scoring Points: Like in Judgement Silversword, the points you collect at the end of each run (except in Time Attack mode) are used to increase your "Option Level" and unlock new features. Anyone can unlock all of the bonus features with enough time and dedication, but skilled players will unlock the bonuses faster.
- Smart Bomb: The "F" powerups, which wipe all bullets from the screen and do slight damage to all on-screen enemies.
- However, collecting it in Advanced will decrease shot power and multiplier, so be careful picking it up. So if you're playing for score, these basically become extra bullets!
- Spiritual Successor: ESCHATOS is one to Judgement Silversword and Cardinal Sins, while the former gained one with Ginga Force. It's save file for the PC has the abbreviation of "jss3", likely referring to ESCHATOS as "Judgement Silversword 3".
- Spread Shot: Nerfed since Judgement Silversword. Except at lowest firepower in Advanced, the spread shot does not have any directly-forward coverage.
- Timed Mission: Time Attack mode. Clearing areas and getting a 1-Up will extend the time limit, finishing a sub-area will freeze it, getting killed takes off 5 seconds, and there are no continues.
- Unstable Equilibrium: Dying not only reduces your multiplier by one, but it also allows enemies to escape in the time that you spend respawning. Enemies that escape during the respawn delay do count towards the multiplier penalty. On Original mode, dying during a large wave of enemies means your entire multiplier will most likely disappear, thereby destroying an entire stage of efforts.
- Weird Moon: The Moon appears to have been corrupted by the alien forces. You restore it when you defeat the Final Boss.
- Video Game 3D Leap: After the 2D sprite-based visuals of its WonderSwan predecessors, ESCHATOS goes for full 3D polygonal visuals but the gameplay remains mostly 2D.
- Year X: The story of ESCHATOS takes place in the year 21XX.