I play a lot of couch coop with my kid but adults would enjoy all these too. Most can be found under $20 on Steam and a lot are fairly lightweight games but have good coop mechanics and can be a lot of fun to sit down for an hour or two with.

• Overcooked 1 + 2 (but 2 really is better) you will love or hate it depending on your personalities, nothing in between. We loved it
• Ship of Fools
• Enter the Gungeon
• Lovers in a Dangerous Spacetime
• Moving Out

On Switch

• Cadence of Hyrule
• Don’t starve together (only split screen on console not PC… Wtf)
• Pikmin