If you're one of the people who just happen to have a low-end old PC, with minimum specs, (ie., have an integrated Intel-HD GPU, 4Gb or even 2Gb ram, Intel Core i3 or i5 processor),
-Then don't worry, there are so many great games that you can run on your machine.
PC gamingPac-ManSim CityQuakeAge of EmpiresHalf-Life
Half-Life 2Call of DutyGTA IVBattlefield,
The point is, there is an excessive amount of good PC games, that can be played in your low spec 4Gb ram PC (some of the games in this list can even be played in a 1Gb or less ram PC) with no dedicated graphics card, and other minimal specs.