Here are a series of intercept scenarios which have been duplicated from Tony Sale's Anoraks Corner on www.codesandciphers.org.uk. I have amended them mainly to make them match the instructions required for the new Virtual Colossus.
Each scenario firstly assumes that the wheel patterns have been worked out already and starts with the basic raw intercept. If you find you're having trouble, there is a hint file for the inital scenarios to get you going or if you're completely stuck - read the final full description giving the break in detail.
The first cipher sent during the Colossus Cipher Challenge in 2007.
This one is easy, you're given MU and PSI starts, just find the CHI starts and you can decipher it
The second cipher sent during the Colossus Cipher Challenge in 2007.
This one is harder, you're given MU starts, find the CHI and PSI starts and you'll beat this one
The third cipher sent during the Colossus Cipher Challenge in 2007.
This one is hardest, you know the wheel patterns but no start positions, just like Bletchley Park, find all the starts and you'll be a Colossus Champ!