Dy-No-Mite Jack
Dynamite Jack plays a lot like a late '90s shareware game. Each level is basically atomic, with your equipment reset every time; mechanics like bombs and line-of-sight enemies are extremely simple; levels can be very short, like seconds long; and the production values, from the art detail to the sound quality, are pretty low. Not to knock the formula: it works, and the gameplay is solid, for how basic it is. And there are plenty of unlockable achievements for each level, so if you're into it, it seems like the game will last you a while.
This may be a revelation for mobile gaming - sincerely, this is more fun and polished than most phone games I've seen - but on a PC, in an ecosystem that's since evolved way beyond this style of game, it's just too simple and antiquated.
Progress: Finished "Walls" (level 5).