Major game companies don’t hesitate to charge an arm and a leg for new releases, with most launching around $60 these days. You may not be aware but there is quite a few older commercial titles freely available, just waiting to be downloaded. Dozens of old school favorites like Doom, GTA, Command & Conquer, Fallout, etc. can be had totally free.
Here is a few of the most popular games:
See the whole list here.