This is what happens when you combine Super Mario and Halflife 2. Map made by me.
If you wanna see what's inside the pipe, check out this video.
• Super Gordon Bros Half Life 2
Download the map here:
http://twhl.co.za/mapvault_map.php?id...
If you're wondering,
NO, I DID NOT USE GMOD. I did it in HalfLife 2.