How do you get level ideas?

[Proxima]

Whilst it is a fantastic option, NeoLemmix doesn't actually include the original Amiga games. Lemmings Redux is a collection of the best levels from DOS Lemmings, Oh No! and other ported versions (Genesis, PSP, etc).

That's not entirely accurate. It's true that NeoLemmix is a continuation of the Lemmix engine, which started as a direct port of the DOS version. But the levels included in Redux try to be more faithful to the Amiga version: the DOS version removes water on many levels, and has lowered requirements on a few levels (notably "Come on over to my place" and "The Steel Mines of Kessel"), and instead of keeping these, we put them back to how they were on Amiga.

[WillLem]

It's true that NeoLemmix is a continuation of the Lemmix engine, which started as a direct port of the DOS version. But the levels included in Redux try to be more faithful to the Amiga version

Fair enough, and I know that by now NL is probably only like DOS in terms of its default gfx and sounds, all of which can be modded anyway. But even so, I'd still say that the answer to the specific question "where can I play Lemmings and Oh No! More Lemmings as close to the Amiga version as possible whilst offering modern QOL features?" is SuperLemmix rather than NeoLemmix.

As well as restoring the levels, several other engine elements such as the UI graphics, menu theming, sprite colours and internal physics have been modelled on the Amiga version during SLX development.

The only thing I haven't done yet is restore the Amiga sound scheme. SLX still uses the DOS sounds from NeoLemmix. The music has all been sampled via the Amiga Paula chip though (albeit an emulation thereof).

One of the main goals of SuperLemmix in fact, and specifically as a fork of NeoLemmix, was to base it more on Amiga than DOS. Obviously, the absolute best way to do that would be to reverse engineer the Amiga game itself from scratch (as Lemmix originally did with DOS). But, by the time SLX development began, NL was already quite far away from its DOS base anyway, certainly far enough to be able to redesign it to a different set of specifications.