From: 
Half-Life: Zombies Ate My Neighbors
// Valve Game Info file
// These are key/value pairs. Certain mods will use different settings.
//
game "Zombies Ate My Neighbors : GoldSRC Edition"
startmap "caganeira"
trainmap "credits"
mpentity "info_player_deathmatch"
gamedll "dlls\hl.dll"
gamedll_linux "dlls/hl.so"
gamedll_osx "dlls/hl.dylib"
secure "1"
type "singleplayer_only"