Games that I put in this category: The first spyro game (not sure about the later ones, havent played) and A Link Between Worlds are both very fun and rewarding to complete and never feel like a chore to do so.
One game that is very much NOT in this category, as is often said, is DK64 lol. But everyone says that. I’ve also heard people say Super Mario Oddessy is fun to beat but not fun to complete, same with BOTW because of the Koroks. People usually say this about SM Sunshine as well but I dont really mind it in this game.
Sidenote complain about the world: Sandbox games combined with my autistic obsessive compulsive need for completionism lead to me playing them with very frusterating habits lmao. No Man’s Sky is the worst for me. I LOVE that game but god the respawning ROCKS ruin the experiance kind of. If the rocks stayed gone, I could use them to gradually explore the worlds I’m on in a completiony way. (Even knowing that like even a single planet is kind of impossible to fully explore let alone the entire fucking universe lol). But I cant!!!
Sorry I need to shove that rant into everything. Completionist mindset also limits me with games like Terraria, Minecraft, and Starbound as well but not as badly because I at least can keep track of exploration in those (Or just dig deep pits in minecraft as I enjoy doing to waste time while I watch streams lol).
I also get myself caught in absurd goals that NOONE expects you to do and the game doesnt keep track of (no achievemnt for it or anything) sometimes like doing all coin runs in Mario 64 or marrying, seeing the 14 star event, and then divorcing every spouse in Stardew Valley lol. (I acutally havent started the second thing but it is sort of in my head as a goal).
This turned into a general rant about how my completionism effects me lmao but anyway thoughts.
I had a lot of fun completing Celeste!
I felt extremely accomplished
when I finished the main story of the game with enough strawberries to get the 2nd best ending. 
So I planned to see if I could go back and get 'em all, and also work my way through the daunting b-sides. 
But when I found out there were still even far more difficult c-sides 
I am sad to admit, I kinda gave up hope of ever truly completing the game. 
C-Sides are usually easier than B-Sides IMO due to their short length.
Checked out the Steam Summer sale only to be quiet shocked I didnt already own Celeste lol. I havent played it on anything to be clear, Im just used to big names like that laready being in my library because Im addicted to collecting on steam.