Anyone who's played Dungeons and Dragons Online (the MMO) for any length of time is familiar with lights out. It was a favorite puzzle for the designers of the earlier-vintage quests, and notably the most popular raid in the game for many years has an entire phase devoted to locking each of the twelve participants in their own lights out puzzle. Low-effort people find a solver, really low effort people beg other people to solve theirs for them. Go-getters learn to solve lights out without a solver.

There's also an infamous quest that ends with a lights out puzzle with a large, arbitrary board (some squares completely removed) while an overpowered, invincible, impossible-to-tank scorrow boss chases you around. And both the boss and the dozen infinitely-respawning trash mobs activate squares when they step on them.

I knew I had played a game like this in the past, thanks for finding it!