Spider Splicers are extremely well-designed enemies, with unique mechanics designed to scare the player as much as possible. The problem with this, though, is that this effect only lasts for so long: once the player familiarizes with their behavior and/or feels more powerful they also lose the element of surprise (with one notable exception). In BioShock 2 this was immediately felt, since the protagonist was a Big Daddy. In this co-op mode, featuring two Big Sisters as the main characters, no less, it'd be even harder to shock the players. To me, the solution would be to introduce even more unconventional mechanics to this enemy type, which'd enrich them in terms of both gameplay and setting the mood. Since there aren't different varieties of this Splicer, hopefully you won't have to deal with a massive wall of text below:
Awarded at random:
- +Damage Against Spider Splicers
- Paralyzing Venom (attacks slow enemies down and prevent them from using movement-based abilities)
- Cannibalism (looting enemies for the first time restores a portion of your health)
Changes: Stage One
First off, every non-Elite Splicer model should be able to be a Spider Splicer, if perhaps with distended limbs similar to the Crawler model. What annoyed me most about Spider Splicers in BioShock 2 was that there was only one Splicer model for them. Instead, the latter could be a Spider-exclusive Splicer model.
Secondly, as I mentioned in my singleplayer version of this article, the Spider Splicers could start out with string/rope connecting their hooks to their arms, allowing them to perform new attacks such as pulling their targets towards them, throwing themselves towards their prey and pulling their victims up towards the ceiling before attacking them. This'd give them a lot more mobility, and could thus also increase their ambushing potential.
Tier One Mutations
- Bloodsucker: Elite Spider Splicer heals itself slightly over time with each attack.
- Envenomed Hooks: Elite Spider Splicer's attacks momentarily distort the target's vision slightly.
- Dermal Chitin: Elite Spider Splicer is immune to movement- and control-impairing effects.
Evolution: Stage Two
Since at this point the players would be better equipped to evade this Splicer's ambushes, it could gain extra power in the form of a new Plasmid: by firing it at the floor, the Spider Splicer'd create temporary webbing-like goo, slowing down everyone touching it and dealing continuous minor damage. When firing it at a target, the latter's movement speed and attack rate would be reduced for a short amount of time and they'd take continuous (but small) damage for that duration. Bar the similarities to a certain friendly neighborhood superhero, this'd further allow the Spider Splicer to split up the players and otherwise manipulate them.
Tier Two Mutations
- Invasive Webbing: Elite Spider Splicer can deploy its Plasmid across a wider area.
- Nutritive Mesh: Elite Spider Splicer heals continuously when standing on top of webbing.
- Clinging Silk: Targets hit by the Elite Spider Splicer's Plasmid have their weapon temporarily disabled.
Evolution: Final Stage
By this time, the players would be savvy enough to realize that they can pinpoint a Splicer's location simply by listening to their voice. In response, the evolved Spider Splicers would be completely silent, and how they came to lose the ability to speak would be visible on them. Though they'd still make the plaster on the ceiling crack as they move on the walls, it'd be a lot harder to locate them. In addition, their complete silence, along with their graphic mutilation, could make them even more disturbing than before.
Tier Three Mutations
- Echo: Elite Spider Splicer can project a voice at a location of its choosing, attracting the attention of nearby targets.
- Anthropophagus: Elite Spider Splicer can heal itself over time by eating from corpses. Can also heal itself instantly by cannibalizing live Splicers, severely damaging them (if not outright killing them) and turning them hostile.
- Ecdysis: When at low health, the Elite Spider Splicer will attempt to escape. Once out of sight it'll shed its skin and heal itself to full, producing a lootable hollow corpse. It'd then ambush the target at a later time. Can only perform this once.
And that does the Spider Splicers! Sorry for posting these at a sluggish pace. I had this laid out for over a week, but the heat over here's sapping my willpower. Comments and criticism are appreciated, as always.