Recently, it’s been:
Monster Strike (mobile) - Multiplayer co-op monster billiards…kinda. One of the most entertaining mobile games I’ve played, and one of the most successful ever (last I knew, it made $3MM/day). Only in Japanese, unfortunately, because…well…I can’t read or speak it. ;p But it’s easy enough to manage regardless, and there’re English resources online for it.
Alchemist Code (mobile) - Kinda-sorta multiplayer co-op Final Fantasy Tactics, and if that idea makes you salivate, then hurry and start playing right now while their Disgaea collab is running (Laharl is probably the best unit in the game). There’s a JP version that’s about two years ahead of the Global version, but Global is awesome and tons of fun.