all areas inside of the way borders are clickable no?
so simple solution is: only use way borders & no paths + you can create additional way borders inside of the main borders (ctrl+left click to create new border/path - I think - I've forgotten the shortcut) to prevent the user from clicking on certain areas of the scene.
using the arrow keys as controls could work quite well for sideways scroller I think?
you can use left/right keys for movement & assign the up key as the action key (the action key part would take a bit of setting up though) - just a thought