I kept going back and forth in my mind about whether or not to recommend this game, but it is free and there’s a lot of things it does right.
2D Collectathon platformer. Left/right moves with momentum, A jumps, B dashes left/right with increased momentum, and X does a “cone rush” (dash attack) in the direction you’re pointing. If you keep holding the direction you were moving after finishing a cone rush, your momentum is maintained, but if you’re not holding a direction when it ends, you’ll come to a dead stop when it’s over–but only for left/right cone rushes; letting go on an upward cone rush keeps you moving upward, like a double jump. I 100%ed the game and never quite got used to its controls.
The game’s first impression isn’t very good. Not only does the first level (after the tutorial) have lots of seesaw-like physics platforms that have boxes fall on them from off-screen, causing them to become heavily slanted and hard to use, but the boss of the first level is really tedious: it does two passes at the top of the screen–where you can’t attack it–before finally flying one pass just above the ground where you can finally deal one point of damage…out of eight HP. Other early bosses have similar problems: the boss of Sand Dunes frequently gets knocked into a spike pit when you attack it (and your attacks are what deal damage, not the spikes), so you have to wait for it to regain composure and jump back out before you can safely attack again. Then, the boss of the game’s first “boss course” does need to be knocked into the spike pit to deal one point of damage, except each time, the boss jumps above the screen and you have to wait several seconds for the boss to come back down…EVERY…SINGLE…HIT. Again, the boss isn’t even that hard–you can easily knock the boss back into the spikes right after he comes back down–it’s just really tedious.
If you can make it past all that, though, you’ll find the game’s level design is mostly pretty good: those seesaws only appear in one other level IIRC, so you don’t have to worry about them much after the first level, and there’s lots of variety and challenge without straying from the game’s core mechanics. However, the game has quite a few spots where you have to run towards small Bullet-Bill-style cannons that can shoot at you from off-screen without warning. Plus, levels are awfully linear for a collectathon, and you don’t have the option to quick-travel to checkpoints, meaning missing one can force you to replay a lot of the level. On top of this, checkpoints can be pretty far apart–presumably to balance the fact your character also has 8 HP, but this means that you can be forced to replay a lot after dying, once again adding unnecessary tedium (especially when what kills you is an insta-kill pit).
Another good detail is that the other bosses are actually designed around having 8 HP, and as such, they don’t make you wait as long before being vulnerable again. That said, the bosses for the Minor Courses get reused with negligible level design changes, and the difficulty curve even just for Major Course bosses isn’t consistent (one of the easiest bosses is the “hard” variant of the Major Course 6 boss).
You also always have a sidekick character flying behind you who points to a collectible in the level that you haven’t gotten yet. This is a really good feature that the dev immediately defeats by having some collectibles in a come-from that can only be reached from other levels, and these specific branching paths aren’t pointed out by your sidekick since the collectible is technically in the other level. Your only guidance is an NPC by the initial dead end who tells you which other level to search in, but besides that, you’re on your own. They could really benefit from being pointed to as well: I only saw the clock level’s inter-level path because I missed a jump, and I didn’t see the power plant’s inter-level path until my second run through because of how much it blends into everything else. Compounding on this are two things that otherwise would have been kinda neat little details: some inter-level paths just lead to an ordinary spot that you can reach directly, and four inter-level paths loop back around to the level you were just at before finally giving you the collectible you were after. The first time I encountered the latter, I assumed it was yet another of the former and backed out to the hub from the pause menu to get the other collectibles in the level, only to realize at the end that I really did have to go that way to get one.
Still, the game wasn’t too bad despite all that, but the main reason I questioned my recommendation is that some solid tiles are easy to confuse for background objects and vice versa. In Doomsday Colosseum, there are single-tile-thick rows of yellow and orange sand against a dark background, so you’d think the darker orange sand is the background sand, right? Nope, the brigher yellow sand is the background sand. The game also has wireframe tiles that are a thin square with a slash through them; it’s not too bad in the easy first level, but it’s really bad in later stages like the power plant and the lunar base, where they’re arranged similarly to their background-object counterpart and don’t have many opaque pixels to distinguish them at a glance. However, the worst example is the Ex version of Richard’s Tower on the hub’s fourth floor: the solid tiles are the same dark grey color as the background, and the eye-catching red tiles are the background tiles!
By the way, the game has some unique water physics, in that water doesn’t alter your physics at all; it only keeps your cone rushes recharged so you can keep doing them as long as you’re underwater. If you’re falling fast towards water at the bottom of the screen, you need to time your cone rush well, lest you pass the water and die in the pit.
Overall, this game is kinda hard to recommend because every good thing it does has a catch. Level design is pretty good, but the controls are awkward; you’re pointed to collectibles you haven’t gotten, but not if you can only get there from another level; large missiles have warnings for when they’ll shoot you from off-screen, but small projectiles from Bullet-Bill-style cannons don’t have warnings. Meanwhile, not every bad thing it does has a silver lining: graphics are sometimes unclear, some bosses are tedious for no reason, the seesaw platforms and off-screen boxes in the first level are just straight-up a bad idea to begin with, etc. All that said, though, the game is free, so you’re not losing much by giving it a chance.