Death Ray Manta | Gameolith | £0.77 (RRP: £2.50)
This is the only kind of DRM we like. Death Ray Manta. Geddit? Either way, this arcade shooter is some of the most zany fun I've had in ages, put together by the magnificently twisted and unmistakeably British mind of Rob Fearon.
However, if you want to download Game Maker Studio's free version on Steam, you can legally get DRM for free here (if you know what you're doing).