Recently we had a discussion (http://www.lemmingsforums.net/index.php?topic=2267.0) on the climber mechanics for V2.00 with respect to low terrain. Regardless what the rule is, it should be applied consistently. However in NeoLemmix V1.35C this is not the case!
If the wall is at least 8 pixels high, a lemming might climb it, even when there is terrain among the lowest 6 pixels. But if the wall is precisely 7 pixels high, he turns around :lem-mindblown:! The reason seems to be some too rigid terrain checks for hoisters.
Example level attached.
While I'm struggling to remember why this is the rule, or how I could've justified it at the time; there is at least a consistent logic here. The consistent rule is - the lemming cannot climb it if there is an overhang on either of the last two pixels that he climbs.
Well, I wouldn't call it consistent logic to have a rule that only applies in one very specific situation (wall = 7 pixels high, overhang = 6 pixels high), even if one can state it in a much more general fashion.
It is perhaps noteworthy that precisely this situation actually appears naturally: Assume you have a pillar style level with a brown stair and want to modify it such that climbers may pass, but usual walkers cannot. The most natural way to do this is to take a triangle piece (object number 8 or 9) and use it to erase three pixels from the top of the second step of the stair. The result is precisely a terrain setup as described above. Of course one can slightly modify the setup to take this into account, but this needs at least one more terrain piece and therefore feels less natural.
It probably is something that should be changed for the big update. I'm probably not going to change it for the small one.