Monolith, is my recommendation, currently on sale for $3.99.

It's a top-down twin stick shooter, similar to Binding of Isaac and Nuclear Throne. With some bullet hell mixed in.
Each full run for me lasts around 30 minutes? But only after getting used to enemy patterns and bosses.
Cool weapon combinations, unlockables, overall satisfying gameplay.

Also there's a DLC coming out, Relics of the Past, around Christmas. Most likely it will be released here too.

What do you guys recommend from the sale?
So far i've copped Necrodancer, Slay the Spire, and Pathologic.

Guacamelee! Super Turbo Championship Edition - One of the best Metroidvania titles of the past decade that's underserved in attention.

Broforce - Arcade-y action mixed with Digdug + 80s action hero surprises, immediately engaging and genuinely fun. You'd be inhuman not to like it.

Both titles under $4.

Darkwood
Excellent horror game that doesn't rely on jump scares. No permadeath on default difficulty.

Populous: The Beginning
The only other real god game apart from Black and White, from the legendary Bullfrog studios.

Startopia
Hands down the best space station sim ever made. In the same vein as Theme Hospital and Dungeon Keeper. Functioning and very pretty widescreen resolution support iirc.

Disciples 2
Grimdark fantasy turn based strategy, on the same tier as HoMM3, only imo with a richer atmosphere and more gripping stories and characters.

Grim Fandengo
Need I say more?

Stronghold HD
Best castle building sim ever made.

Rayman Origins
A properly good platformer with excellent replayability.

World of Goo
The case could be made that this is the best puzzle game ever conceived.

I have Monolith wishlisted but I think I'll wait more.
I for sure reccomend taking CHUCHEL at 74%. Best price. It's like an humorous interactive animated book with easy puzzle and mini-games, its strenght is in the animation. It really makes you smile, it's the game I would have a child to play. Lacking the small human, I'll play it my self.
https://www.gog.com/game/chuchel