Loddlenaut

I played the demo of this in the last festival and really enjoyed it. I bought it pretty much immediately on release as it's such a nicely made, relaxing game. It's primarily a game about cleaning up the ocean floor using a variety of tools, but it also features little sea creatures called Loddles, which you clean, play with, feed, and find homes for. It's relatively simple all round, but it's clearly made with love and I found myself looking forward to playing it on the Deck each evening. There's also an upgrade tree which you buy using trash you clear up from the ocean.

Pros

Generally it runs well on the Steam Deck
Loddles are cute
Relaxing
Multiple interesting ways to clean stuff
When you clean an object, it bursts out in coral and flowers
Sometimes cleaned objects also emit oxygen
There's an upgrade tree, bought with objects you find cleaning up
There's also a cooking and toy station for Loddles
As you reach certain thresholds while cleaning an area, the lighting and the murkiness of the sea visibly changes, which is quite satisfying

Cons

The Steam Deck struggles a little when there are microplastic clouds nearby, or lots of trash on a scan
Inventory management with a controller is really annoying. You need to unload everything you cleaned into trash collectors, which means: open the inventory, move the cursor to an object, moving it to the top row of the inventory, close the inventory, unload the item, picking up the Bit you get, open inventory, select the Bit, move Bit down from top row. Repeat about 15 times each time you come home