Half-Life timeline

Release order is when each Half-Life game launched in the US (1998–2020)—including HL1 expansions before Half-Life 2, and Alyx last in 2020. Story order follows fiction: Half-Life at Black Mesa, optional parallel expansions, then Half-Life: Alyx (five years before HL2), then Half-Life 2 → Episode One → Episode Two. Alyx is last by release but mid-saga by story. Portal and Portal 2 share the universe but stay FAQ-only—no locked official dates for every crossover beat.

Flat-screen Gordon-only → Half-Life on Steam → Half-Life 2 → Episode One → Episode Two. Add Half-Life: Alyx before HL2 if you have VR and want the strongest pre-HL2 chapter—or after Episode Two if you want zero Ep2 prologue spoilers (see Alyx FAQ). Skip Opposing Force, Blue Shift, and Decay on a first pass unless you love HL1 parallel stories. Portal is optional but recommended before Episode Two for Borealis context—see full-universe FAQ. Black Mesa (fan remake) is optional—not official rows here.

Two paths fans actually use—pick one goal. **Gordon-only (fastest):** Half-Life → Half-Life 2 → Episode One → Episode Two; add Half-Life: Alyx when you have VR. **Full universe (lore-heavy):** Half-Life → optional Opposing Force / Blue Shift / Decay → Portal → Half-Life 2 → Episode One → Episode Two → Half-Life: Alyx → Portal 2. Portal games are separate puzzle series on this page—not numbered Release or Story rows—but Episode Two's Borealis plot pays off if you know Aperture lore. Many newcomers skip Portal entirely and still follow Gordon; neither path is wrong.

Half-Life: Alyx is set five years before Half-Life 2 in City 17—you play as Alyx Vance, not Gordon. **Story order:** finish Half-Life (HL1), then Alyx, then Half-Life 2 and both Episodes. **Play order:** most community guides put Alyx after Episode Two because the opening recaps Episode Two's ending—playing earlier risks spoilers unless you skip the prologue. It shipped in 2020 after the Episodes but is not Episode Three. You need a VR headset; flat-screen mods exist but are not official.

All three take place during the same Black Mesa incident as Half-Life—different protagonists. Suggested order after HL1: Opposing Force → Blue Shift → Decay (optional). None are required for Half-Life 2. Decay is PS2-only officially; PC players use the Decay restoration mod. Gearbox developed Opposing Force and Blue Shift; Decay was Gearbox co-op on PS2.

Valve announced a trilogy of Episodes after Half-Life 2; Episode One and Episode Two shipped in 2006–2007. Episode Three was never released—Episode Two ends on an unresolved cliffhanger. Half-Life: Alyx (2020) advances lore but is not Episode Three. As of June 2026 there is no official Episode Three or Half-Life 3 release date.

Valve never published one locked calendar for the crossover. **Portal 1** broadly sits after the Black Mesa incident and Combine invasion era—writers described it as post-invasion; Combine forces tried to enter Aperture before Chell's tests (per Marc Laidlaw). **Portal 2** picks up after Chell's long stasis—how many years passed is intentionally vague: development notes once floated far-future numbers, while in-game stasis counters, relaxation-vault expiry, and facility decay fuel fan debate from decades to much longer. We keep Portal off Story rows because no single official chronology satisfies every source. Play order guidance lives in the full-universe FAQ—not a definitive in-fiction year chart.