A brief discussion on the forum mentioned the possibility of platinum and diamond talismans after I was shown a replay of my level "Deep Freeze" where all 80 lemmings are saved (anything above 78 requires extremely precise and fiddly gameplay).

Besides challenges that are harder than gold-level talismans (although this is open to debate), I am in support of a higher level, such as emerald or diamond, for those challenges that require ridiculous precision, but I'm wondering if actually a better option would be to have a level of talisman that is hidden in the player... that is, you can see the level has a diamond talisman, but you don't know its prerequisites, possibly because very few people know about the solution or the prequisites give too much of a clue as to what you have to do.  For example:

Granted you can cheat by opening the level in a text editor or the NeoLemmix Editor, and there may be other ways to disguise the solution.  Still, maybe something can be salvaged from this.

So I've been making subset levels for a while now.  This one isn't a subset per se, since one of the one-way walls has been reversed, but I figure it makes a great "part two" level.  Have fun!  It uses Genesis music, which it expects to find in the "genesis" subdirectory of "music".

Name: The gate trap Lemmings (part two)
Difficulty: Moderately Hard

I would say I'm in two minds about the triggered background object, because I envisioned a gas flame that only reaches full power if a lemming walks over it, incinerating them, but at the same time it must act like a fire object and kill all lemmings, the idea being that the triggered object is the flame roaring to full power, while a separate, mostly invisible object, probably with just a small pilot light, is the actual fire object.  Being able to disable that background object would ruin the effect a bit (it's fine to be invisible in clear physics mode).

I would go with the third option personally.  Let it be the level or pack creator's choice.  Timed bombers, besides the execution difficulty, have some tactical differences in how it interacts with other skills - for example, the Cloner, since if the lemming has the countdown when cloned, the clone gets the countdown too.

Thank you for your feedback!  I'm glad I have some potential!
I can't wait to see your video playthroughs!

Still not perfect as it now overhangs the sloped wall by the exit. Best solution is to probably move the water back a bit and put some blue balls under the slope to fill up the void that will appear.  i gather the Redux version isn't suitable for speedrunning.

For me, the one time that I remember being legitimately scared from a game - in that my adrenaline raced, my heart pumped and I just froze in fear (and died in-game) - was when I found the Pac Man ghost in E6M10 of Wolfenstein 3D.  I hadn't found the secret level of Episode 3 yet, and this moment just completely freaked me out because it was completely une unlike anything I had seen in the game (and that's alongside mutants and the fake Hitlers in E3M9).

I decided to update Blockout a little bit by making the platform near the start much thinner...
...ensuring that a large range of Blocker tricks are used in a single level.