  We introduce a simplified model for platform game levels with falling
platforms based on interval graphs and show that solvability of such levels
corresponds to finding Steiner cycles or Steiner paths in the corresponding
graphs. Linear time algorithms are obtained for both of these problems. We also
study these algorithms as streaming algorithms and analyze the necessary memory
with respect to the maximum number of intervals contained in another interval.
This corresponds to understanding which parts of a level have to be visible at
each point to allow the player to make optimal deterministic decisions.
