Yes, the original Tomb Raider (and the entire rest of the franchise) is available on Steam right now. There in all its resplendent glory, Tomb Raider comes complete with clunky controls and clunky landscapes.
All of that aside, the original Tomb Raider shines because it's mentally stimulating without being overwhelming. There's space to take the environment in and think about your next steps without having to speed through levels or an ambush of enemies.
The version on Steam is the original MS-DOS version that did not have save crystals, so do not make the same mistakes I made.
Buy Tomb Raider on Steam for $6.99.