very complex map for portal. its called ss_orangebox.
Since there is no official SDK released for Portal, I created this map
with Half-Life 2 Singleplayer Hammer.
If you want to take a look at how I created this map you can decompile it with VMEX. This map is a bit different compared to the original portal maps. There are always help signs on the wall in the original maps, like how to place the portals to come further in the map. Also you will find signs of where to find the cube. Another one is "the cake is a lie" not that THAT helps you... In this maps there are only arrows. They show you where you can go, but how to come there? Find out yourself... There is an exit sign because after play testing I found out that most people didn't knew where the exit was.