I am looking for an old style rpg that I can play by myself. is there such a thing? I was kinda thinking the munchkin series was like that
If you are just looking for a tactical dungeon crawl, the DMG of 4e specifies how to do so.
If you are looking for more story, look to Mythic Game Master Emulator. It is designed to be playable solo.
But ultimately, if you are looking for just the tactics, I would suggest looking into a solo playthrough of one of the D&D board games, e.g. Castle Ravenloft