I've been playing Trainyard on my iPhone. I'm having fun. But I've reached A Barrel Roll and I'm not getting past it. I can get the cars down to two purple and two green but I don't have enough free space at that point to work out a merging pattern to get them down to one of each. I started over and tried to work out a system of pre-merging the blues, reds and yellows but then I didn't have enough space to do a final merge. And I don't really know what to try next.
There are places I can watch a walk-through and places that will just show me a winning screen. And I could move on. but if anyone here plays that game and can give me just a nudge in the right direction, I'd rather go that route.