One thing that has always bothered me a bit about Oblige/ObHack is that secrets are fairly rare, and no real effort is made to hide the secret areas.
Today's snapshot of ObHack fixes this. Now, ObHack generated maps will always have at least one secret on a level. In addition, it's not quite so trivial to find a secret; you need to pay attention to find it.
The ObHack snapshot (20090404) can be downloaded by clicking on this link.