This is an amalgamation of Binary Land by Hudson and Bomberman, also by Hudson. I guess I really like Hudson more than I realized.
The player controls the two bomberbots simultaneously. The primary character (the one marked with "!") will respond to your directional input, whereas the secondary will move in the horizontally mirrored fashion like in Binary Land . But unlike in the original game, you can press O to change your primary at any time.
Pressing X will drop a bomb, both at the same time. The bomb can destroy the blocks and kill enemies. The bomberbots don't take damage from their own bomb blasts, but they can damage each other. Killing three enemies without taking damage in a row grants a shield, and the combo is displayed on the top right. (Sadly this is the only bonus from combo.) Dead enemies may also drop hearts which add one life.
The doors will open when there is no more enemy left in the level, and the stage is cleared when both bomberbots reach the exit. They don't need to be in two different doors; if you somehow get them to overlap and they end up in the same door tile, that also counts. Some levels are symmetrical but most levels aren't, and this is more of a puzzle than an action.
The game consists of 15 short levels. The first level is always a short tutorial level, the rest of them are shuffled in randomized order.
Story-wise, this is related to Bomba Cum Laude and Ka-Ka-Kaboom! as the characters re-appear; the chronology can be in any order. A lot of code from Bomba Cum Laude is also recycled here as well.
The game supports the 2-player mode where each player takes control of one bomberbot. All story cutscenes are removed from this mode and here, they can take damage from their own blast like in Bomberman. The immunity to own bomb was added to the single player otherwise it'd make it too difficult, but when one player controls one character this is probably not as needed. Two players share the same stock of lives so blowing each other up is not recommended.
I haven't tested multiplayer as much since I only have two arms. I'm not really keen on playing or making multiplayer games on PICO-8 but this game felt like a natural fit for it. One player or another may start with limited options to manoeuvre at the start of a level, but the other player should be able to get you out of there.