SuperLemmix 2.4 Now AvailableAt last! Apologies for the delay on this one!
This is a major update, so it's strongly recommended that you download this as a fresh installation, and copy any mods/levels/styles/etc from your old copy into the new one.
(The plan is still for a future version of SLX to include online update/download/installation features, removing the need to download everything each time there's an update. In the meantime, thank you for your patience and support.)
What's new...
New Features
Re-inroducing SUPERLEMMING! 
We now have Superlemming mode once more, with some additional tweaks so that it plays more like the OG; as well as the game playing at 3x normal speed, players can't use FF or Rewind, and cannot assign skills whilst the game is paused.
New Talismans - "Play in Classic Mode" and "Play Without Pressing Pause". These have been extensively tested and seem to work fine, but please do let me know if you spot any bugs with these. These talismans should fail if a replay is loaded at any time (including Mass Replay Check!

), but in the event that hitting restart causes the game to pause or auto-replay, the player has a few seconds to exit replay and unpause the game.
Turbo-FF speed implemented - it's accessible via hotkey (mapped to "T" by default), or the FF button can be set to always Turbo by toggling "Activate Turbo Fast-Forward mode" in the Options menu. It's frameskip-based to mitigate any slowdown due to graphics rendering.
The level sides are now one-way-forcefields! Any lemmings who reach the side will respond to it in the same way they'd respond to a Blocker or a one-way-forcefield - in some cases, the lemming turns and continues with the skill (e.g. Builders, Miners), in other cases where it wouldn't make sense for them to continue, they stop and turn (e.g. Platformers, Bashers).
"Poison" is now its own object, and turns any lems which contact its trigger area into zombies! All styles that have already had their water renamed to "poison" (e.g. orig_marble) have this object included.
Radiation and Slowfreeze objects have been added. These are based on the original objects in old-formats NeoLemmix. Each sets a 10 second countdown timer to the lemming - Radiation leads to a Bomber, Slowfreeze leads to a Freezer. This is brand new to SuperLemmix (literally implemented the day before this post!) so testing is needed and bugs are likely. Plans are for these objects to eventually have variable countdown timers, sounds, and either state recolouring or a "glow" effect for the lemmings.
The Assign Fail sound (which made a brief and unsuccessful appearance in 2.1)
is now fully implemented and working - a sound is played whenever a lem can't receive an attempted skill assignment, and the steel sound is used if the skill assignment fails because steel. It also works for highlit lemmings!
Previous assignments are no longer overwritten when playing in Replay Insert Mode! Instead, the new assignment fails (the assign fail sound plays to alert the player that the assignment is impossible on that frame). This is a placeholder feature until I can figure out how to allow same-frame assignments to different lems, but it works, and it's way better than accidentially overwriting a previous assignment.

If a lemming has begun to exit before time runs out,
they now count as saved!
Gameplay now ends if the lem dies whilst playing a single-lemming level
in Classic Mode.
Freezers are now drawn in original sprite colours, so that sprite recolouring works for all states. The "Freezing" and "Unfreezing" states have a separate overlay drawn over the top to provide the gradual-freeze-fade effect, and the Frozen lem is drawn behind the actual ice cube rather than in front (which also makes more sense anyway).
Freezers are protected against zombies during the Freezing & Explosion state as well as the Frozen state. They remain zombie-vulnerable during the Unfreezing state.
Freezers can now be assigned to Timebombers, meaning that they can stop a Timebomber in midair, and can be used to more accurately position a Timebomber for explosion.
Freezers now explode 2px lower when assigned to Swimmers, enabling following lemmings to "dive" below the water's surface (similar to NeoLemmix's Stoner/Swimmer skill interaction).
Jumpers now "bounce" when they hit terrain - they turn, and complete the trajectory of their arc facing in the opposite direction. Turns out this is how Jumpers behave in L2; I genuinely didn't realise this until
after making the decision to implement this behaviour!
Shimmiers now have an extra pixel's grace for overhead terrain checks - they now fall at 3px instead of 2px.
Music now plays in the Menu screen! It can be customised per-pack, and toggled on/off via the Audio Options menu. The default menu music is a 38-second sample of an Amiga disk drive loading

The Postview screen text is now per-line recoloured (modelled on the Amiga recolouring). The plan is eventually to make this user-customisable.
The SuperLemmix window caption now displays level title and save requirement info. It also displays "Mass Replay Check" when in MRC mode.
The save count is no longer displayed as a negative number in the panel - to compliment this, the panel now displays the save count in red if it hasn't yet been met.
The Level Select screen now has a "Reset Talismans" button, so players can reset their talisman progress on a per-level basis. Very handy for level testing, and when replaying an already-completed pack!
The Grenade graphic now animates during its arc, and
it can be customised per-style (the Grenade graphics are now stored in styles in a new "grenades" folder alongside lemmings, objects, terrain, etc). Please note that BOTH resolutions need to be accounted for when creating custom grenade graphics. Also note that the actual Grenade destruction mask (as well as the Spear masks/graphics) are still in
gfx\masks and cannot be customised, for obvious reasons.

SMS fire and marble styles have been updated to include "lava" and "poison", as with the OG fire and marble styles.
GigaLem's Millas and Flopsy's SonicLems have now been fully updated to include all SLX sprites. The plan is to eventually have all custom sprite sets updated in this way, but this will take time so will be done over the course of several styles updates.
Level Info icons can now be customised per-style (the level's theme chooses which style is used for these), as well as per-levelpack. Theme is preferred, and defaults will be used if no customised versions are present.

Sounds have been added for Spear hits, and for the Laserer!
General Updates
A new line for "Fewest Total Skills" has been added to the Postview screen text.

All level info icons have been updated.

Postview Jingles are back!

Every level in the DMA Compilation pack now has a "Play in Classic Mode" talisman.

Platformers, Bashers and Fencers are now cancelled when reaching a one-way-forcefield. This prevents unnecessary skill continuation when the lemming turns around.

Lemmings are now drawn to FOUR separate layers, meaning that there is now much more flexibility in the way that they appear in the level. The most notable difference is that Freezers now appear behind the terrain, so they don't overlap adjacent pieces and the ice cube is fully displayed in CPM, and all explosion graphics are drawn behind active lems to aid visibility when framestepping.

FF, Turbo, Rewind and Superlemming modes all toggle the HQ minimap off to conserve rendering power.

Sleepers are no longer neutrals - so, no state recolouring, but they still can't receive skill assignments.

Default scroller text has been updated to include a few more credits and development info.

Added a Double-click event to the Level Select treeview, so that level labels are loaded correctly when opening a pack's tree nodes.

The Xmas levels are now in the root folder of the DMA Compilation pack

Pressing Up/Down on the Group sign in the Main Menu stops at the highest and lowest rank respectively, rather than cycling infinitely. This makes it easier to know which order the ranks are in when the names are ambiguous.
Bugfixes
Talisman info popup now displays centre-screen for all orientations.

The last Sleeper in the level now finishes its animation before the level exits.

The level select screen caption now says "SuperLemmix Level Select" instead of "NeoLemmix Level Select".

The Shimmier skill shadow is now displayed in all relevant states - the previous bug meant it only displayed when the lem was a Climber.

The user is prompted to restart SLX if bass.dll fails to initialize.

Rewind no longer touches user config, at all (it previously toggled "pause after backskip" off). Rewind has also been fixed so that entering and exiting Rewind mode never pauses the game.

Countdown and Highlight arrows are no longer drawn behind other lemmings.

Traps now don't affect lems, and Disarmers don't fix traps, whilst the lem is in any of the Freezer states and over a trap's trigger area.

Default Previous/Next Skill hotkeys are now mapped to Down/Up instead of Up/Down - this seems to make more sense.

Fixed bug which caused the Replay "R" graphic to occasionally flicker on and off when changing the RR in Classic Mode.
Editor Updates
Ctrl + Wheel now scrolls the level horizontally, whilst Shift/Alt + Wheel scrolls the level vertically (when zoomed in).

Shift + LMB now selects/deselects individual pieces as well as Ctrl + LMB.

Horizontal Drag is now controlled by Ctrl + RMB as well as Ctrl + Alt + LMB.

Vertical Drag is now controlled by Alt/Shift + RMB as well as Ctrl + Shift + LMB.

(RMB on its own still performs drag-to-scroll).

"Activate Superlemming Mode" checkbox added.

Support for "Play in Classic Mode" and "Play Without Pressing Pause" talismans added.

Support for Poison, Radiation and Slowfreeze added.

Many UI updates
* Further refinements to scrollbars
* Moved Custom Move numeric to Settings menu instead of Pieces tab (seems more appropriate there)
* Updated all menu dropdrowns to display the hotkey to the right
* Condensed "Tools" and "Options" to a single menu
* Moved "Play Level" and "Validate Level (which now has a Ctrl+F12 hotkey)" to the File menu
* Significant improvements to Hotkey dialog.

The state of the AutoStart checkbox is now remembered per-level when Closing and re-opening the Editor.

"Display Tabs" is no longer an option - tab display is the default and only option. This is necessary due to the various UI updates that have happened since Editor 2.0.

All dialogs (Hotkeys, Options, About, Validate Level, etc) now appear centre-screen.

Fixed bug in which a num up/down box was displayed for Kill All Zombies talisman when it didn't need to be, and
wasn't displaying when it
did need to be for other talismans.
Have any comments? Please use the
SuperLemmix Discussion Topic.