Better name needed, haha.
Poster A posts a boss fight (or how it works), but keeps it brief (600 characters maximum).
It can be one that exists (in which case posting the boss's name and work they're from (in bold) is required), or a new one that's never been seen before (so far you know).
Poster B then posts what they think of it; watching videos on existing bosses is allowed. Then, their turn, with the boss fight post and...
An alien with a giant mechanical gunship capable of unleashing bullet hell, with lasers, bombs and such. You get... a little toy plane and shurikens, maybe other ranged sub-weapons.
(Palenque - La-Mulana)