In your spreadsheet you forgot to factor in that the self repairs only happen
once every three seconds. The repair rate also depends on the difficulty
settings, currently easy: 0.1, medium: 0.05, and hard: 0.05 in
map/difficulty_params.dat.

Finally the equations indicate that Tux would be frozen for well over a minute
in some circumstances.


The main reason why we are changing this, is that Tux can be frozen for too long.

How about the attached: