What's a mad scientist without minions? There are plenty of those in Rooms of Doom, and you, being a mad scientist, will subject them to terrifying trials as part of your evil research. Don't worry, you can always make new minions—and you will. Lots of them.
Rooms of Doom is an endless runner, like many of the games published by Yodo1. Crossy Road comes to mind, of course, but this sort of simple, highly accessible gameplay seems to be its hallmark. The game is made up of a series of random rooms filled with dangers. Navigating them is as easy as tapping at the right time, but the mechanics of each room are different. Some are like Flappy Bird and others are more like Crossy Road. The longer you survive, the more coins you get and rooms you unlock.
Rooms of Doom is a free-to-play game, but I've played it for a bit and have not seen much reason to buy anything. It seems to be a very gentle take on FTP. Like other Yodo1 games, you get lots of free gifts. If you're really into the game, you can buy any of the rare minion characters for a buck.