So I haven’t been playing for quite some time, but I remember the grenade… I think that I’ve manage come up with something even worse, but this time for aliens, worse than my previous “time dretch” suggestion.
The Ultra Basilisk should be a somewhat stronger version of a normal Advanced Basilisk, but without its invisibility and gas abilities. Instead, it should get an even better ability: radiopsyonic camouflage, which should only last for twenty or so seconds, requiring a lengthy recharge afterwards.
The ability should have two main effects: the radio part confuses human defenses, greatly reducing their accuracy and range against the Basilisk, and also restores the 1.2 behaviour where you could fool turrets by moving side to side in front of their sensors.
The psyonic part is where the true power lies: far from mere invisibility, it causes the humans to simply deny that it even existed while the ability is active. Note that the human has to observe (see or hear) the actions for the effect to apply to them.
An Ultra Basilisk attacks a human a few times. The human will lose health, but will not be aware of it. If the human is then killed by an alien, it will seem to the player that they died for no reason while still having health to spare.
An Ultra Basilisk kills an armory while a human watches. To the human, it appears that literally nothing happened. The player can still “sell” and “buy” weapons using it, but nothing will happen in reality. For example, if you buy a Lasgun from a non-existent armory, it’ll appear as if you have bought it, but in reality, using it will simply fire your previous weapon.
An Ultra Basilisk attacks and kills some base turrets. The humans see neither the Basilisk, nor the fact that the turrets are firing back at it. Then a Dragoon attacks the base. To humans, it would appear that the turrets still exist and are attacking the Dragoon, and if they “kill” it, humans will start denying the existence of the Dragoon the same way as they would be denying an Ultra Basilisk.
An Ultra Basilisk blocks a running human. To the human player, it would appear that they’re still running, when they are, in fact, not. There’s a caveat: the player will only be able to see what their real body sees; if the real body loses sight of players that the human should be seeing from their imagined position, those player should be replaced with bots. The lifts and doors should appear to work as well. The human should snap back to their real location after some time has passed though.
The effect should be contagious: being around a psyonically contaminated human makes you to deny the same things as they do.
The effect should be insidious by avoiding inconsistencies that would give it away where possible. Here are two examples of inconsistency mitigations:
Any humans infected by another human who has an imaginary structure will only begin to imagine that structure after they re-enter the area after having spent some time away from it, to make it seem that the structure was built by other humans while they were away.
If a real structure is built in place of an imaginary structure while an infected human was away, the real structure should take precedence. If the infecting human was watching, the real structure should only replace the imaginary structure after the human leaves the area for some time and re-enters it.
Of course, sometimes inconsistencies will be unavoidable, such as players passing through imaginary structures. There should be a cool graphical effect for those cases though, instead of a boring polygon intersection.
There should be a cure that costs 300 credits and makes you immune for a minute, but doesn’t tell you right away whether you were under its effect or not.