The original Half-Life and Half-Life 2 are now just $1 each on Steam, leaving you with little reason not to catch up on the series before Half-Life: Alyx releases in March. Whether you've played through the first two Half-Life games or not, it's hard to pass up on these two extraordinarily well-loved games at 90% off the sticker price.
If you really want to dive deep into Half-Life with one complete package, there's another fantastic Steam deal (thanks Wario64) you might want to consider. The Half-Life Complete collection includes Half-Life 1 and 2, the enhanced Half-Life: Source, the Half-Life: Opposing Force expansion, Half-Life: Blue Shift, Team Fortress Classic, and Episodes 1 and 2, all for just over $6 (about £5).
Of course, this is all in anticipation of the hotly-anticipated Half-Life: Alyx, a full-length, VR-exclusive prequel to Half-Life 2 coming March 2020. Naturally, the decision to limit the game to VR platforms saw mixed reactions, but it's still very exciting to see a proper return for the Half-Life franchise after the most recent entry, Half-Life: Episode 2, released way back in 2007.
If you are looking forward to Half-Life: Alyx, it's worth mentioning that it's 10% off on Steam right now at $53.99. It seems Valve is doing everything it can to make returning to Half-Life as financially feasible as possible, which is wise considering you'll need at least 12 gigs of ram (via TechRadar), not to mention a VR setup, to run the game properly.
Speaking of cheap games, keep an eye on the best Black Friday game deals to keep the savings coming.