For whatever reason, Valve's gamemodes_server.txt.example file is really complicated and has some random errors in it. It makes it very difficult for people to run custom maps on their servers. Here is a much simplyer gamemodes_server.txt file for anybody having issues.
Code:
"GameModes_Server.txt"
{
"gameTypes"
{
"classic"
{
"gameModes"
{
"casual"
{
"maxplayers" "20"
"exec"
{
"exec" "server.cfg"
}
"mapgroupsMP"
{
"mg_absurd" ""
}
}
}
}
}
"mapgroups"
{
//
// Map cycle groups
//
"mg_absurd"
{
"name" "mg_absurd"
"maps"
{
"cs_thunder" ""
"de_mirage" ""
}
}
}
}