Every mad scientist needs minions, and Rooms of Doom lets you put those minions to the test with its simple one-tap gameplay. It's an endless runner of sorts, but with a lot more variety than other game sin the genre. The assortment of test chambers changes each time, and tapping does different things in them.
For example, a tap in the Barrel Blast room tapping launches your minion from one barrel to the next. In the Boxing Brim, a tap reverses the direction of a treadmill so you can avoid being squished. The longer your minion survives, the more minions and rooms will be unlocked. It's a free-to-play game with things to buy, but you get lots of free stuff, too.
Rooms of Doom: Free ($0.99-$99.99 in-app purchases)