Yes. Unfortunately the devs were under very tight time constraints, and 1999 wasn't exactly a time when distributing patches for games was really even possible - or profitable. There are a lot of things that could have happened that didn't happen - and that TCRF article is highly incomplete (flooding, spiderwebs, voice lines, Tunnel Transport are all entirely lacking from the article).
I prefer a different method turning the NERPs scripts against themselves:
Turns out slugs can't suck depowered buildings nor the non-selectable tile of a building (so they can't suck the Ore Refinery with the way I've placed it), and also turns out slug AI has very many holes in it and they're stuck there permanently. As the game always requires 10 slugs for this crystal level, there are indeed 10 slugs stuck in holes - accent on stuck - so as you can see I don't even need Action Stations on
Other anti-slug strats, in order of efficiency, include:
- Teleporting up your Tool Store, which prevents drained crystals from popping out anywhere thus crystals never drain
- Teleporting down a boatload of LMLCs every time you have the crystals for them so you're never above the crystal threshold for slugs, then teleporting them all up in one swoop to get the crystals you need
- Rushing your way to the crystal goal by going to the far East before the slugs can suck you dry
- Using monster jank to recharge crystals (monsters can eat depleted crystals, but if they are then destroyed, the crystal will drop as recharged)
- quitting? "The only winning move is not to play" comes to mind...
There is a death animation specified for them: it's the same anim as when they dig into their hole. You can kill them, but miners won't attack when monsters are retreating and slugs retreat at 50% HP (monsters will also retreat at around 20% HP if they haven't been one-shotted by a Laser Beam), so you need to use either manual methods (eg: a Mining Laser) or mods.
Slightly unrelated, but retreating is handled by a PainThreshold value in the CFG. Slugs have 50, so they run away at 50%. (Setting this to 90 would mean they run away after a single shot). Rock Monsters have 20, so they run away at 20% HP - and also, for some possibly not terrible reason, monster HP drains over time, so providing they're not carrying a boulder (which somehow overrides this) monsters will run around, get their HP low, and then run back into walls. Of course, you don't see any of this if you use Laser Beams and Electric Fences to one-shot them.
And yes, they leave, and then come back immediately, because that's how poorly the slug script is programmed. It's not the same slug coming back for more: it's just another slug, because the script specifies "for X crystals there must be Y slugs on level."
Interestingly frozen slugs still count towards the timer despite being totally inactive, so if you mod Slimy Slugs to be freezable you can equip all your miners with Freezer Beams and slugs become a minor nuisance, but not the nightmare they usually are