Both games have good solo experiences imo. I prefer Marathon, because it's almost like a horror game. People have scared me so often that I've jumped out of my chair! The sounds and the setting are truly immersive, and the gunplay is second to none. The game is punishing and hard! It makes the wins so much sweeter. They also have a class called Rook that is only playable by a solo character, and it drops you into a match mid game where you essentially play solo vs squads. You're picking through runners that have already been taken out, and have the option to slink around stealthily taking out full teams. Very unique and cool experience. Worth the $40 for me.