Not I follow how this increases game speed over time. Under Forced Movement I thought these settings were game speed settings not time settings?
AFAK the values are pixels per second. So let's say you have Min 200, Max 600 and Increase 10, then at the beginning it goes 200px every seconds, next second 210, 3rd second it goes already 220px and so on until reaches the max and maintains that speed. When you die and restart or it starts from the Min speed again.
During the game speed increace, the player gradually falling behind and ending up off screen. How to avoid that, and make the player follow the same game speed while it increasing?