Celeste is 90% off, Kingdom Come Deliverance is 80% off, Braid Anniversary Edition is 75% off. All worth it imo.

Love some diver Dave, and balto.

Depends on your definition of "new" and "must-have".

• Grapple Dog 75% off — momentum-based grappling hook platformer with a very funky soundtrack and Nitrome-style 2D art (spoiler: the dev was a Nitrome artist)
• Cobalt Core 25% off — deckbuilding in space! There's an actual plot with an interesting cast of characters. The board game-style positioning mechanic was what sold me on the game.
• Cassette Beasts 40% off — creature collector with an identity that isn't just "indie Pokémon". Cool worldbuilding, heartfelt story, grown-up mechanics, and imaginative monster designs that avoid the "animal + element" formula.

I just picked up Dread Delusion, Shadows of Doubt, and Stellar Tactics. I played demos of Dread Delusion and Shadows of Doubt a while back, and both of them blew me away; the former just launched out of early access and the latter is supposed to do so before the end of the year. Stellar Tactics is one that's intriguing, but I haven't played it yet. I've been playing Fallout 2 lately, and it made me want to find a CRPG that was more successful at what Starfield was trying to do; I typed in some tags into the Steam search, Stellar Tactics was what I found, and I think it'll scratch that itch. Stellar Tactics is also in early access, and it's been in early access since 2016 with no end in sight, but it's very systems driven, so I'll likely be okay with playing it early anyway.

Monster Sanctuary! Scratches the Pokemon itch but way better than any Pokemon game ever has

I don't know how must have it is, but I've been enjoying Isles of Sea and Sky, a sokoban type puzzle game currently 10% off until July 11th (currently $17.99). I'm pretty sure it's maybe a month or two old at least.

Crab Champions is not exactly new (I think it's been in early access since 2023), but it's really fun and currently just $7.49