In a similar vein to the
recent discussion about Oh-Noers turned into Swimmers (which should no longer be possible), I want to draw your attention to the possibility of Swimmers interacting with water specified as "only on terrain". I've come up with the attached level yesterday, and wanted to discuss to what extent this behaviour is intended before I base further corner-case stuff on it
. Two issues came up as a result of this:
1) Climbers, Swimmers, and on-terrain water
As it was explained to me in the above-linked thread, Climbers are technically located one pixel inside the wall they are climbing. Consequently, if that pixel of terrain is covered by water, a regular lemming would turn around on the wall as usual, but in the moment you assign a Climber to him, he will drown inside the wall.
A lemming who is a Swimmer already when starting to climb will climb up the wall normally. The same is of course also true if the on-terrain water starts only two or more pixels into the terrain, so that the climber can place its foot pixel inside the non-water-covered terrain on the outside. (To try this out in the attached level, switch off the pre-assigned Swimmers from the hatch and move the on-terrain water objects one pixel to the right.)
A lemming turned into a Climber first will start drowning inside the wall; if you then assign a Swimmer to the Drowner, the lemming will start swimming in the opposite direction for one or two frames before turning back into a Walker (with the Swimmer skill still assigned to him, of course).
2) on-terrain objects and terrain removalAs I've found out in Lemmings-World-Tour design during the construction of a level called "Ring of Fire", which never got made precisely because of me finding out how the mechanics actually work in this case: If you remove the terrain behind an object set to "only on terrain", be that object fire or water, the trigger area still remains active, even though the object is no longer visible. Usually, such removal is only possible by using Bombers (although, in the case of traps, other destructive skills may also work, because with traps, the trigger doesn't cover the entire image of the animation).
Thus, where I intended for the lemmings to bomb through the ring of fire so that the crowd could actually fall into it, the lemmings would still burn, only that the fire objects were no longer visible. So they'd burn in an invisible flame in mid-air.
Water behaves the same way, but since it's not quite as lethal as fire, Swimmers will interact the same way as they normally do with the now-invisible water.
Is this intended? From a "fairness" standpoint, it seems very confusing to the player that an object they can no longer see still affects the game mechanically. We no longer have the option to create invisible objects, but apparently you can still make objects invisible during level playing
...
If the mechanics were to be changed so that only-on-terrain objects remain visible when the terrain behind them is removed, this shouldn't affect any levels mechanically. For example, the attached level would still work - although I'd probably change the title, in that case, because the illusion of the Swimmers "flying" would no longer be present. Instead, you'd have to "free the water" out of the terrain to actually be able to use it.
Generally speaking, I think the option of on-terrain-only objects should definitely remain, since it's required to accurately replicate the aesthetics of original Lemmings levels (such as "We are now at LEMCON one", Fun 20, and its rerun).