Agrajag: Depends on game preferences. And gaming philosophy.
For example, one could do a split of 2x5+10+2x15 and drown in a whole load of games, or go for a big whammy (for the sake of the argument: e.g. Minecraft) and keep the rest for a future sale opportunity.
Then there's the multiplayer aspect.
Whatever.
Kamiko for the cute little cheap pixel game appeal. Three characters, combo and speedrun supporting adventure-y game. Good value for five bucks.
Enter the Gungeon (and/or Neurovoider maybe) for dungeon crawling in pixel form. Twin stick shooters.
Golf story, because Pixel Golf is good entertainment, even though the RPG elements are basic and badly explained. Lacks a bit polish in the stability and bug eradication department, but too fun to ignore.
Maybe Mummy Demastered for a pixely Metroidvania. It's surprisingly good for being attached to a dead franchise. No prior franchise related knowledge required, thankfully.
Opus, for your Indie-slightly-philosophical-barely-a-game game needs. I cry everytim. No but seriously, look at YouTube for the core gameplay loop, it's a rather fun star gazing/pixel hunting game. Also on mobile I think. Unlocks a dev audio library where the idea and decisions behind the game are explained. Interesting stuff.
Stardew Valley for the date, hack and slay farm simulator with pixel graphics.
Also rans:
Shantae because why not. It's Shantae, and the idle animation is bollocks. Very Wayforward.
Letter Quest remastered because playing (and paying for) F2P flash word puzzle games is a thing. Music is wildly inappropriate though. Even the alternative non-remastered one. Wait for 60+% off. Gets extremely grindy.
Koi for when you need to be one with your inner fish. Better on sale, tbqh, but still quite nice. Swim around, find things, unlock things, evade enemies. Play the demo, you might like it.
Cat quest, because paying for a slightly upgraded mobile game can be worth it if you dig the cat word puns and cheesy story. Combat is simplicistic, but it has a certain charm.
Pinball FX3/Stern Pinball Arcade (depending on whether you like phantasy or real flipper tables, respectively). Hey, Flipper games are fun. Don't knock them. One table is free, anyway, so give them a try.
Ironcast, a match three-or-more FTL crossover game born from a kickstarter. Lacks that certain something, that spark that keeps bringing you back, but definitely fun for a good while and Steampunk is always nice. Strange controls if you don't use the touchscreen.
Monster Boy. Old game with new paint job that can be switched to the old pixel graphics and sound on the fly because it's an elaborate ROM hack. Rather impressive, actually. Of course, it's still Monster Boy, so dunno if that's your thing.