Alright, I haven't played "The Writer" yet (don't spoil it for me!), but what I got from the ending is that the whole time we were playing through "The Signal", Alan was just rolling on the ground and it was all in his head? 
 
Nothing has moved forward, nothing has moved back? 
I'm very confused by the ending of The Signal. 

-Spoilers (not for 'The Writer') -
 
Yeah you are right. I think at the end of the game Alan ends up in the lake when he switches places with Alice.
So in 'The Signal' you are playing through what he was writing whilst inside the lake (kinda like a dream sequence) and at the end he realizes he still stuck in the lake house and he was the writer.