Why Did Earth's Special Forces Move from Half-Life to Sven Co-op?

Updated

Earth's Special Forces (ESF) moved its development from Half-Life to Sven Co-op because Valve's November 2023 25th anniversary update to Half-Life broke the mod's memory budget. According to the ESF team's March 14, 2024 update, the update left Half-Life without the "LargeAddressAware" (LAA) flag, capping the game at 2GB of memory, and ESF's content had grown large enough to hit that wall. Rather than patch the executable themselves and risk a VAC ban, the team switched to Sven Co-op, which has source code access and can use up to 4GB.

What the Half-Life update actually changed

The anniversary update was good for the base game but disruptive for the modding community as a whole. Two effects mattered for ESF:

  • Many mods broke. The only way to keep playing some of them was to switch Half-Life to its legacy beta branch.
  • Memory behavior changed. Valve adjusted Half-Life's memory usage, which produced more "out of memory" bugs.

The legacy branch workaround has a catch that applies directly to ESF: it works fine for mods that don't depend on Steam functions, but ESF does rely on Steam's connectivity. So even the temporary fix has an expiry date — once the legacy version starts having trouble connecting to Steam servers, ESF:F would stop working there.

Why 2GB became a hard wall

Half-Life doesn't have the LAA header flagged, so it can only address 2GB of total memory. Had Valve enabled LAA in the update, the ceiling would have been 4GB and the whole problem could have been avoided.

For ESF, 2GB was no longer enough. The team notes that their base Trunks model alone is as large as all of the Half-Life models combined. That's the practical meaning of "hitting the memory wall": the game didn't just run poorly, it didn't work.

Why the team didn't just patch it themselves

Enabling the LAA flag on their own was technically possible, but the team was concerned about shipping a mod that could potentially trigger a VAC ban. They chose not to take that risk.

That constraint is the reason the platform decision came down to who could legitimately change the engine's memory behavior — not who had the better tooling.

Why Sven Co-op was the answer

Sven Co-op, unlike ESF, was given the Half-Life source code after requesting it. That access let Sven Co-op alter the game to use 4GB of memory. Moving ESF there resolved the core memory problem.

The team acknowledges the irony of the situation, but the trade-off has been concrete progress:

  • Every model and character is now in the game, mostly animated and working.
  • What's still missing is each character's unique transformation animations and their bonus tiers.
  • The team no longer has to close and reopen the game to change maps.

What still needs fixing after the move

Switching engines solved one class of problem and exposed another. The old version of FMOD that ESF uses for sound is outdated enough to cause its own issues, and it still needs to be addressed.

There's also cleanup work on the clutter system so map changes work flawlessly — the stated goal being to stop things like rocks spawning in the air. On the content side, Dalte is working on bonus tiers for the characters and on setting up audio for each character's transformation.

What this means for players

If you're waiting on ESF:F, the practical takeaways are:

  • The move is a fix, not a reboot. The project continues, now on Sven Co-op.
  • The memory blocker is resolved. The 2GB ceiling that stopped the game from running is no longer the constraint.
  • Remaining work is content and cleanup, not a return to the original problem: transformation animations, bonus tiers, transformation audio, FMOD, and the clutter system.
  • The old path is closing. Playing on Half-Life's legacy branch was always temporary for ESF because of its Steam dependency, so Sven Co-op is where the project's future sits.