Meet the new Lara Croft.
Where do old electronic games go to die?
They often survive as free downloads on the Internet.
Check at downloadanystuff.org and the Wiki list of games released as freeware.
There is also C:Dos Abandonware and oldgames.nu or free game downloads. The last includes many manuals.
Perhaps better would be just this Google search for "abandonware game downloads" and look into the top sites. Squakenet looks like one of the best and directs you to other sites for info and downloads. Here are the links for UFO: Enemy Unknown aka XCOM: UFO Defense and Epic Warhammer. You might need to download the dosbox to play these on a modern PC.
Getting back to the picture - here is the original Tomb Raider 1996.
You do give up something in the old games - sweeter graphics.
I'm adding a couple of games to check out.
Starship Troopers: Terran Ascendancy
Wargame Construction Set 3
Armada 2525: Deluxe Edition or here.
There is a free version of The Political Machine 08.
What looks like the best space game worth paying for - Galactic Civilizations II: Twilight of the Arnor. This replaces my Space Empires V recommendation - except for the price as Space Empires is now available for less than $8.
I also highly recommend War! Age of Imperialism for $6 or similar at Amazon. (I picked up a great deal with the shipping cost much more than the game price right before Christmas.) Think of W!AoI as advanced Risk with pretty smart AI opponents. Make sure you download the update patch. I like Eagle Games board games and this PC version is better than the board game.
PCWorld has an article on some recent games converted to freeware.