Setting the gravity to something below 256 causes the current setup to move less than 1 full pixel each frame, which in turn means that the character cannot stay grounded. This is because the grounded state sets downward velocity to 0 each frame.
A possible fix is to set the downward velocity to a higher limit on grounded, but this could cause problems for the way solid-actors are setup.
Setting the gravity to something below 256 causes the current setup to move less than 1 full pixel each frame, which in turn means that the character cannot stay grounded. This is because the grounded state sets downward velocity to 0 each frame.
A possible fix is to set the downward velocity to a higher limit on grounded, but this could cause problems for the way solid-actors are setup.