If you mean 100% achievements on Steam for example, I really enjoyed doing that with the following games:

• Slipstream (2018): arcade racing game, 7.5h to 100%

• SpongeBob: Battle for Bikini Bottom - Rehydrated (2020): platformer with some collectathon elements, 13h to 100%

• Polyball (2017): think Super Monkey Ball, but a bit faster and stronger momentum iirc, gets quite difficult later on, and although the amount of content isn’t ridiculous, it’s very very hard to manage the requirements for 100%. My playtime is 59h, but I kept playing after 100% to get into the top 10 leaderboards on a bunch of levels, so I think it was more like 30-40h for 100%.

• The Stanley Parable (2013): narrative game with some unconventional puzzle elements, 40h to 100%, but not really: one of the achievements is “play the game for the entirety of a Tuesday”, so that adds over 24h. Another achievement is to not play the game at all for 5 years. Some people love this silly stuff, some hate it, up to you :)

• Firewatch (2016): narrative game with exploration and some puzzles, 6h to 100%.