Run the game, start a server with only defaults, Team Deathmatch and game modes like Capture the Flag enabled. When you spawn, open the minigame menu and check what's there - does the game mode selector appear, do the tabs ("General" "Teams" etc.) appear? If either is gone, there's a problem. Close the game, get the console.log file from your Blockland folder, upload it to some website and post the link here.