I'm supposed to believe one man made this when entire triple-A studios couldn't find fun with an orbital telescope?
Anyway, are there any other indie games of this quality, regardless of genre?
Pizza Tower released last year and it was extremely fun and polished, felt just like a cartoon turned into a videogame and cranked to the max, i can't say if it is as good as Turbo Overkill cause I only played the demo, but Pizza Tower kept me coming back many times to do replays or just trying to get the P ranks, if you like the sort of highly replayable and fast to finish platformers then it's 100% a must play.
As for other stuff, Deep Rock Galactic is a dwarf coop mining game with a really nice style and lots of different missions to do, it's also full of dozens of little details and small stuff to do between missions, + it even has elf racism.
On the smaller side, SCP NTF is a nice total overhaul mod / game for SCP Containment Breach, made by Third Subdivision Studios who previously worked on the post 1.0 updates for CB, it's not polished, it's janky as fuck and ugly, but the waves mode is solid and the campaign ain't half bad even if unfinished, there's also SCP CB MP which i got 20 hours or so from just trying to beat the game over and over again as fast as possible with my friend (you might notice by now i like replaying shorter games and quickly :v)
Dimensional Slaughter wave based FPS, kinda a mixed bag, but when it clicks it's really fun, still in EA which explains a lot of why it's still unrefined, but even in EA i got a good couple hours out of it.
You can also check many Half-Life 1 and 2 mods released these last few years! Entropy Zero 1, 2 and Uprising, Evacuation, Swelter, MMOD, Raising The Bar Redux Division 2 (they also did a Gregori mod which is sweet), C.A.G.E.D., Echoes, etc... etc... just go check moddb and download every cool mod you see, even the more mediocre mods have a couple good exploration or combat sections just from how solid the goldsource / source engine systems are
uhhh more fangames / mods, Sonic and The Fallen Star feels like sonic on the saturn, Time Twisted is basically Sonic CD 2, Triple Trouble, Project 06; non sonic stuff you can find Voxel Doom 1 and 2, dozens of map mods for Black Mesa, thousands upon thousands of Pokemon and Mario ROMS that feel like official sequels.
And if all else fails, you can always browse itch.io by top sellers price free, there's always usually 1 or 2 curious things to try out and some really high quality ones (Mindustry and Shattered Pixel Dungeon are my recommendations if you want something of actual quality to play in mobile or to just fuck around on PC)