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VScript Survivor Manager

!survcount <number> - Set the survCount setting and refresh it in-game. This will spawn in the appropriate amount of survivor bots, handles the auto-management of number of survivors and saves permanently across all games in it's settings file.
!survkick - Remove a bot in your crosshair, or nearest to it.
!survbot <number, leave empty for 1> - Manually add survivor bots.
!survorder <character list> - Change the survivor order the Auto-Manager spawns bots in. Leave empty to reset to default survivor order.
Example: !survorder b z e f n c l r z l
!survswap - Takeover control to your crosshair's nearest survivor bot. Will not work if you or the bot are pinned, downed, or dead.
!survfix - Re-enables the Auto-Manager if you screw up the bot count.

Manage more than 4 survivors in your local game. Play with 8 survivors, and/or bypass sb_add's strict limits in your sv_cheat-fun session.
Fixes the general issues with the bots crashing upon kicking or takeover, so even Admin System's L4D1 bots will not be crash-prone most of the time.

Warning: Special Infected and survivor players/bots share 18 slots. Add too many survivors and you can block special infected from spawning. This is hard-coded and unchangeable, requires a Metamod Source plugin[github.com] to increase the slots to 32 max. Check Technical Stuff for a tutorial on how to install this.

This mod does not have any way to increase any infected count, stat, or other options to balance the additional survivors.
For now, try getting another mod to increase or decrease difficulty.
- Special Infected Synchronization
May require manual tweaking.
This one is a Sync-Only version with no AI changes, but on the mod's page you can get alternate versions that change the AI to be more aggressive.
- Chinese mod called MoreSI
May require manual tweaking.
Not recommended for English users.

If you want more than 4 human players to join, you need an 8 player lobby mod.
Lobby mod 1
Lobby mod 2
Lobby mod 3
There is a stupid strict limit of 4 human players in-game in campaign lobbies that can only be modified by Sourcemod. This is a separate limit that does not care about your lobby slots.
VScript cannot modify this.
The only other way is to turn the gamemode into a "Versus" gamemode. Sorry for disappointing. :(

Link to mod's Github Repository[github.com]
How to install L4DToolz
Click here to know about other features of this mod like changeable settings.