Good couch co-op sale finds?

I don't do co-op much anymore, but I used to play Sackboy with my younger brother several years ago and remember having fun. Have you played it? The graphics look cleaner and more colorful and detailed.

I play couch-coop (or nowadays Steam Remote Play Together) with my kids, colleagues and friends (in three different groups, each having different tastes) all the time for many years now.

We have made lists of currently about 2.300 Steam games that support local 4-player and a list with over 650 good local 2-player games. I would post a link here, but then the mods would most likely suspend me for violating the rules and spamming or whatever, so I will just tell you to go to my steam profile for the links if interested. Be warned, though - too much choice can be overwhelming.

Most of the games I've played with others are more couch vs/party rather than couch co-op
Nippon Marathon
Boomerang Fu
Marooners

But for co-op games, maybe you could try the Trine games?
Also Moving Out
Unravel 2 Not on sale, unfortunately.

And was tempted to pick this one up My Singing Monsters Playground in this sale. The gameplay looks a lot like Marooners, above.

so, that's a few anyway that I can think of, quickly.
Used to play a bit of these 2-4 player, but not so much anymore.

https://store.steampowered.com/app/850320/PHOGS/
I played this one long back thanks to the Cozy thread via TragicBronson himself. I always felt it would be best as coop rather than solo. Cyrrently, not on sale, but frequently is.

https://store.steampowered.com/app/336440/Super_Cane_Magic_ZERO__Legend_of_the_Cane_Cane/
and
https://store.steampowered.com/app/1306720/Mayhem_Brawler/
are historical low priced if I am not mistaken and both seem fun.

I would also suggest https://store.steampowered.com/app/1135230/Ember_Knights/ that I have enjoyed with my kids and they liked Boomerang Fu also that has already been mentioned.Trine series is really great as well if you into that kind of coop gaming.