If modern computer games are out of the reach of your budget (or the capability of your video card) you can always find free and GPU-friendly games at Free Oldies, a massive catalogue of free and abandonware computer games.
Free Oldies is a large catalog of free and abandonware games. You won't find any modern games here with huge system requirements. You will find hundreds and hundreds of games from the last 30 years that are freeware or abandonware. The "Adventure and RPG" category, for example, has 600+ entries.
If you have a game title in mind you can search directly for it. Alternately, you can search by category, letter, or year of release if you're casually browsing. You can rank games and see the rankings others have made but, rather frustratingly, you can't sort your search results by ranking. Other than the lack of sort-by-rank the search interface is more than sufficient to find games. Free Oldies only catalogues the games, the actual files are stores on other retro gaming and file drop sites—popular games usually have several mirrors.
If you're new to playing old games on modern hardware, make sure to check out previously reviewed DOSBox to play DOS games on newer computers. For another source of free games, check out previously reviewed RemainInPlay.