I have an X220 with an i5-2520M, I don’t use it for gaming but I have briefly played Half-Life 2 with it and it was comfortably playable.
So I would say mid-2000s titles and before will be fine. It really depends o the age of the Thinkpad you want is, and the age of the games you want to play.
You’re never lonely with all your Demodex friends.