It would have to be either Zelda or SSB cause Zelda as great and epic single player games and there are a lot of them if u count handheld/console editions! But SSB is, arguably the best multiplayer fighting game ever in terms of just having fun in that pick up and play sorta style which after years of it coming out, I still pull it out when my friends come over and we have fun playing it. So yea, either Zelda or SSB
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850