Helpless creatures don't stop a charge (at the end of the Movement During a Charge section):
https://www.d20srd.org/srd/combat/specialAttacks.htm#charge
that's what the d20srd rules says but in this game it blocks the action:
https://www.flickr.com/photos/193336132@N03/51280000852/in/album-72157719481838766/
the kobold barrier negates the charge movement.
Also, you can cross a helpless enemy square without penalization (Moving through a Square -> Opponent):
https://www.d20srd.org/srd/combat/movementPositionAndDistance.htm
In the game, a character without overrun cannot pass through a helpless enemy and if has the feat, the cost is doubled:
https://www.flickr.com/photos/193336132@N03/51280002672/in/album-72157719481838766/
https://www.flickr.com/photos/193336132@N03/51280921563/in/album-72157719481838766/
theoretical cost of 10 but it aggregates to 15 after the overrun penalization is added.
Of course, there is an exception to the rule where some exceptionally big creatures cause that the squares they occupy count as a difficult terrain and doubles the movement cost. The rules doesn't specify what minimum size is needed for this enormous adversaries so it'll be at the DM judgement.
I think these rules will be nice for the game: strengthen certain spells, increase the possibilities of manoeuvring in the battlefield, moving without penalization through those now open squares and adds the urgency of returning a character to the normal state to avoid greater evils when enemies can now breach the lines and go for the weaker second row.