Sonic Mania is a really lovely homage to the classic 90s Sonic the Hedgehog platform games. Featuring more or less the classic gameplay, and expanded versions of the original levels, with lots of secrets, surprises and easter eggs for fans of the original. On my recommendation a friend of mine bought it for her daughter's birthday recently but her daughter will now have to prise her mum off it! Currently on sale at 30% off (£11.19). The one complaint I have about it is the lack of females in the roster of 5 playable characters.
Butcher is a Doom-esque aesthetic, very violent side-scrolling shooter/platformer, currently on sale at 70% off (just £2.69, the price of a coffee). I've played it for about 10 minutes during coffee breaks and it's fun, hard, and pretty intense. The sound track is great, and available to buy separately but only if you own or buy the original game from the same store, which is a strange restriction. It's also on Spotify.