Personally this was an Idea I wanted to suggested to the community as to recreate and mod each level from Lemmings 2 and mod the solutions to fit NeoLemmix and arrange their order based on difficulty.
I would also note that there needs to be ways to make alterations to levels to substitute for objects that don't exist in Neolemmix (Chains, Cannons, Trampolines. etc)
These are all the levels in Amiga/DOS Lemmings 2: The Tribes that have objects that cannot exist in Neolemmix:
Beach 4: Coastal Suction Function (Chain)
Cavelem 1: Audex Powder (Dinosaur Catapult)
Cavelem 3: Mortal men doomed to die (Trampolines)
Cavelem 4: A stompin' good time! (Dinosaur Catapult)
Cavelem 5: This Is The Pits ! (Chains)
Cavelem 6: Ain't No Time (Dinosaur Catapult)
Cavelem 7: Deadly Exit (Dinosaur Catapult)
Cavelem 8: Wilma! (Dinosaur Catapult)
Cavelem 10: Ah'm No Done Yet (Dinosaur Catapult)
Circus 1: LIGHTLINES.... (Cannon & Trampolines)
Circus 2: Lemmings In The Family (Trampolines)
Circus 3: We're Coming Home (Trampolines)
Circus 5: Big Top Time (Trampoline)
Circus 6: HEADACHE (Cannons & Trampolines)
Circus 8: PLAY THAT FUNKY LEMMING (Cannon & Trampolines)
Circus 9: The Carpet Capers.... (Cannon)
Circus 10: Swingz and Roundaboutz! (Cannons & Trampoline)
Highland 3: Stop your ticklin' Jock! (Trampolines)
Highland 5: DONALD WHARS YER LEMMING (Chain)
Highland 7: In memory of McAngus (Cannons & Trampoline)
Highland 8: The White Heather Club (Chain & Cannon)
Medieval 3: ALL IN A KNIGHTS WORK!! (Catapult)
Medieval 7: UNDERGROUND (Catapult)
Medieval 10: JUST JOUSTING AROUND (Catapult)
Outdoor 2: Swing/Roundabout Theory (Chain)
Polar 2: Ice Ice Lemy (Ice)
Polar 4: DANGER THIN ICE ! (Ice)
Polar 8: Snowed In ! (Cannon)
Polar 9: Its all up hill ! (Cannon)
Shadow 5: Swingadingding (Chain)
Shadow 6: The School Gate. (Cannon)
Shadow 8: Goossen's Inferno! (Cannons)
Space 8: Odyssey (Chain)
Sports 1: Ceci n'est pas une pipe. (Trampolines and Gas Pipes)
Sports 5: Blow Back.... (Trampoline, Gas Pipes and Valve)
Sports 7: The Sun Sign Selection (Chain & Trampoline)
Sports 8: Run the Risk (Trampoline)
The teleporters in Space 8 through 10 can be replicated despite Teleporters being different in Neolemmix than in Space (Neolemmix Teleporters are one way but you could stack teleporters and receivers on top of each other (Although you might have problems with lemmings teleporting back & forth for the rest of eternity.)) Polar 7: SLIPPIN & SLIDING has the skater as a skill despite not having any Ice in that level.
An example to alter levels is Beach 4: Coastal Suction Function. Look at the Genesis version of this stage compared to the Amiga/DOS version. That version replaces the chain with water to kayak or Surf through (For Neolemmix you could simply make a lemming a Swimmer and if the Laserer doesn't make it into the new build, use a Digger pickup skill to free the others). Everything else is pretty much identical. In fact, the Chain is completely omitted from the Genesis version.