Update Serious Sam II to v2.066 with this patch.

Changes:

Implemented Deathmatch game mode
It is now possible to execute a script file from the console (exec script.cfg)
Added samListPlayers() console command - displays the list of all players in the 'playerindex playername' format.
Implemented banning of players by IP address (permanent or temporary).
Implemented map list and map rotation - map list can be specified either in a cvar or through a file.
Added falling damage.
Added damage impact - knockback from explosions.
Increased player speed for deathmatch games (12.5 m/s).
In DM, player runs faster when using the chainsaw.
Players dop the current weapon when killed (DM only).
It is now posible to disable items, weapons and powerups.
Player can be gibbed (DM only).
Implemented the in-game voting system (votes for next map, map restart, kicking players, temporary player ban).
Added the 'only if stronger' option to auto weapon change setting.
Chat message sound is much louder now.
Added support for multi-core in physics solver (disabled by default).