[Bacardi]

yeah, there is no server setting for gamemodes_server.txt

If you still want different gamemodes_server.txt settings for forked servers

You can try test:

// To customize your server, see gamemodes_server.txt.example

"GameModes.txt"
{
	"gameTypes"
	{
		"classic"
		{
			//"value"				"0" // Valve default "game_type"

			"gameModes"
			{
				// Classic Valve default game modes "game_mode"
				// 0 = "casual"
				// 1 = "competitive"
				// 2 = "scrimcomp2v2"
				// 3 = "scrimcomp5v5"

				"casual_custom1"
				{
					"value"			  	"4"
					"maxplayers"		"20"

					"exec"
					{
						"exec"		"gamemode_casual.cfg" //Use Valve default settings
						"exec"		"gamemode_casual_custom1_server.cfg" // Override config file
					}

					"mapgroupsMP"
					{
						"mg_casualsigma"	"0"
						"mg_casualdelta"	"1"
						"mg_dust247"		"2"
						"mg_hostage"		"3"
					}
				}

			}	
		}
	}

	"mapgroups"
	{
	}

	"maps"
	{
	}
	
	"botDifficulty"
	{
	}
	
	"maptypes"
	{
	}
}

So if you run other server with game_type 0; game_type 4
+ You can use another maxplayers value and gamemode_ cfg file.
- This will brake some players GUI (loading screen, errors in console etc. etc.) Not good method