I used to have shittiest known PC to men so I had nothing to play but mediocre indie games that didn't require much processing power. That's why I couldn't get into newer gen games even when recently I got a proper setup. So from my experience, Elder Scrolls (Oblivion-Skyrim), Valve games (Counter-strike, Portal, Half-Life, Team Fortress 2) and GTA games are the ones I always come back to re-play.