You can now play their copy of L4D1 using your own Steam account and save your own achievements. Free Weekends
Add the game to your Steam Wishlist to get email alerts. How To Left 4 Dead 1 For Free
These events usually coincide with a $0.99 to $1.99 sale price if you decide you want to keep it forever. You can now play their copy of L4D1
The L4D2 community is much larger, making it easier to find free online matches. Steam Family Sharing and Special Infected.
Look for promos around November 17th (the game's anniversary).
Steam often hosts "Free Weekends" for classic multiplayer games.
You get the original L4D1 maps but with L4D2’s weapons, melee items, and Special Infected.
