ok gotta catch up but some of these are pretty difficult to answer considering the types of games I play
Day 21 - Game with the best story. The ones which allow you to create your own story ;)
Day 22 - A game sequel which disappointed you. I wasn't that impressed with Civ V before its dlc's released, it just wasn't the same as Civ IV. I warmed up to Civ V eventually though.
Day 23 - Game you think had the best graphics or art style. Super duper realistic graphics aren't that important to me, so I'll go for "art style" over "graphics" on this one. I think Don't Starve has a pretty nice art style, does a good job at making certain monsters look terrifying (looking at you, Deerclops).
Day 24 - Favorite classic game. I think most games that count as "classics" are a bit before my time haha. Although Tetris is timeless so I'll go with that.
Day 25 - A game you plan on playing. I wanna play Oxygen Not Included, idk whether to wait for later in development/steam sale or get it now.
Day 26 - Best voice acting. Overwatch does have some pretty sweet voice acting.
Day 27 - Most epic scene ever. ...is it bad that the HOTS/Overwatch crossover animated short comes to mind?
Day 28 - Favorite game developer. Paradox obvs. also Blizz and Klei are pretty cool too I guess.
Day 29 - A game you thought you wouldn't like, but ended up loving. This is where I say Overwatch again, but also Heroes of the Storm. Both come from genres I had next to no experience in before playing them (unless you count Splatoon and that one time I played Smite but never touched it again because I didn't like the controls.) I only started playing Heroes of the Storm a few days ago and it's growing on me. Have been watching videos on how not to be a noob.
Also, Civ V, post-dlc. See above.