Well, I jsut went through the catacombs, hating those dogs.
any idea how much further till we finally can use those portals?
I'm not quite sure, but I think you mean the circuit keys needed in the crystal castle. This is optional. To get further you have to go to the left where the waterfall is. There you have to swim up the pool of water from the bottom to build up momentum so you can jump high enough. The rainforest leads to the ruins.
Oh yeah, in the rainforest you also get an ability, so I have to correct myself.
yeah I got it by now.
Now I'm (unwillingly and unintentionally) exploring all the catacomb like placs, each with their boss fight and chase sequence.
just got my 4th cube thing, currently in the place where you can change the moving paltforms' direction with the switch stone.
currently mostly backtracking to actiate all the portals I have seen so far.