Game was good. I had trouble with your momentum conservation physics until I realized that they didn't exist. You can flip in mid air to gain or lose forward momentum. Helps a lot.
There is a visual cue for linked tunnels. You just have to look at the background of the tunnel you are in right now. It changes when it forms a new, valid connection.
 "The Pix"){kind=icon}
 "GravityBot HD"){kind=icon}
 "Strand"){kind=icon}
 "Once In The Cave"){kind=icon}
 "Ripple Dot Zero"){kind=icon}
 "Spaceplane v.1"){kind=icon}
 "Garden of War 2"){kind=icon}
 "FIVE"){kind=icon}
New prices will be reduced.