I'm in the middle of putting together a collection of titles that represent some of the best that the Bundle for Ukraine has to offer.

Currently a work in progress but would love for people to recommend and link to suggestions for games to be included!

https://itch.io/c/2317160/best-of-bundle-for-ukraine

My game Déjà Vu is in the bundle and it gets really good reviews. (well at least the Xbox version does, haha)

I'd definitely recommend my puzzler Newtraction, though I may be a bit biased

🔗 https://zexsoft.itch.io/newtraction

Thanks for this list! It will make it a lot easier to go through all of these games.

I liked Don't Escape: 4 Days to Survive and it has Overwhelmingly Positive reviews on Steam so maybe try it :)

https://midboss.itch.io/rom - Pretty humorous point and click game.

https://mattmakesgames.itch.io/celeste - Hard but fair representation of fighting against depression and anxiety.

https://river-crow-studio.itch.io/learn-japanese-to-survive-hiragana-battle - Good for learning one of the Japanese alphabets.

https://river-crow-studio.itch.io/kanji-combat - Same as the above.

https://dj_link.itch.io/quest-of-dungeons - Fun top down dungeon crawler.

https://chrisnzl.itch.io/tallowmere - Fast-paced roguelike platformer dungeon crawler.

My collection of games I've played & would recommend: 

https://itch.io/c/2315700/games-ive-played-liked-from-bundle-for-ukraine

I would highly recommend ZeroRanger. I'm not an expert shmup player, so it was pretty challenging for me, but I enjoyed it quite a bit. I bought it at full price, and I was completely satisfied with it.
https://system-erasure.itch.io/zeroranger

I'd recommend https://siactro.itch.io/toree3d and https://siactro.itch.io/macbat64

Here's an update. (Two are already in the OP's collection, but still it probably doesn't hurt to mention them again.)

GNOG is in the bundle now. It's actually the first in the list, so I guess it's not a surprising recommendation, but still: highly recommended. It's a collection of beautiful, escape-room-like puzzles without any text:

https://ko-op.itch.io/gnog

I now played A Short Hike and it's awesome - everyone should take a few hours and play through this:

https://adamgryu.itch.io/a-short-hike

I haven't finished it yet, but I'm enjoying Inmost so far:

https://chucklefish.itch.io/inmost

Ynglet is a cool little game too:

https://triple-topping.itch.io/ynglet

Update: Micro Dash!

https://inarisoft.itch.io/micro-dash

At first sight, it looks and sounds like a straightforward clone of an 80s game (Boulderdash), complete with 80s graphics and sounds. So why would you play it, with so many prettier games in the bundle...?

Because of the awesome levels and puzzle designs, and the many secrets!

There are many levels where at first I thought "this level just isn't possible", but after taking a break, I found an out-of-the-box approach. Then after fine tuning the execution and details for quite a while, I finally completed the level within the tight time limit. That's a great puzzle. The game is definitely not easy and has a few rough edges, but I've been completely engrossed by it recently, and hardly played any other bundle games since I started with Micro Dash. Check it out if you like challenging retro gaming!