Steam World: Heist. Tactical turn based shooter. Somewhere between Worms and X-Com, definitely on the lighter side. It's the same vibe as Steam World 1 and 2, but now the cowboy robots are in space. It's perfect for the Deck and easy to pick up for a few minutes at lunch or in between meetings.
Heist has a story and preset levels. Each level is usually a different ship you have to board and clear. They're all connected by a sort of star map. The objectives for each level are preset. Though, the level layouts may be generated. I've rerun a couple and I remember the layouts being a bit different.
SteamWorld Dig 1&2 are platformers. I really enjoyed them. The gameplay for Heist is different but it still feels like the same quality.