Well the iGPU isn't the most powerful on market but it will surely play TF2 and CSS well. Always lower your anti aliasing options, shadows turned off, anisotropic filtering to the minimum. Basically you just keep trying settings until it's playing decently fluid or to your liking.
A dedicated GPU will help, assuming you have a desktop.
If this is a laptop, increasing the ram speed and amount would help with the VRAM for the graphics.