A Left 4 Dead update released this morning removed some Survival exploits and bugs, including one where Tanks sometimes stopped spawning after 15 to 20 minutes.
According to the patch notes, Survival exploits were removed from The Terminal, Last Stand, The Crane, The Boathouse and The Warehouse.
The exploits in question most likely refer to standing in areas where the AI cannot easily reach the players, if at all, similar to the infamous “Jesus rock” in the Death Toll finale.
In addition, the leaderboards will now only show your personal best time rather than your team’s best time.
The full patch notes are copied below:
Survival Mode Changes
- Darkened the Lighthouse background movie and increased the contrast with the user interface elements
- Chapter selection is now available when creating a Survival lobby
- Single player coop now works correctly after playing Survival online
- The correct game mode will be set when playing back a demo
- Changed holdout server spew to be development only
- Stats are no longer updated while viewing a demo
- Correctly update the leaderboard based on the player’s personal time, not the team best time
- Show the player’s best time in the scoreboard
- Removed Survival exploits from The Terminal, Last Stand, The Crane, The Boathouse and The Warehouse
- Fixed tanks sometimes not spawning after 15-20 minutes