ToME WikiRavenRed: Quick 'n' dirty idea here. Invisibilty is granular for the player (i.e. it has a variable "power" which influences how effective it is on Monster AI). Monsters have a differential chance of seeing an invisible player according to a few different factors. For players, however, "See Invisible" is a binary one-power-sees-all. My suggestion would be to make the player's chances of seeing an invisible monster in any given turn subject to the "power" of both the monster's invisibility and the player's see invisible ability (usually derived from magic items or artifacts). This could create the effect of monsters swimming in and out of the player's field of vision, requiring the player to make an educated guess as to where the monster has moved in the turn since it wavered out of sight.
Your chance of seeing a monster could beomce SEE_INVISIBLE in INVISIBILITY_POWER. Even a relatively low power gives you a decent chance of detecting at least an occasional movement, wheras you'd have constant sight should your see invisible power be greater than the monster's invisibility power.
Any comments?
2cworth and counting...
Derakon: Sounds similar to my suggestion: IdeaArchive/Probability clouds for partial invisibility
ReenenLaurie: I guess things standing still will be much harder to spot... Or the player, when he stands still he should be harder to spot too. I imagine myself when I realise I'll be losing a fight, wear a ring of invisibility, and run around a corner and hide - stand still. Maybe ready a bow or something. The fact that you're not moving - and the corridor is not so well lit as the room (though what happened to your lantern?) - should obscure you more from the monster.
AerdanRunestar: I like the idea, and I'd also like to see a similar effect with fog [which would be an alpha-channel transparency effect]. [Unrelated: I fixed your link, Derakon.]
Remuz: I like the idea, even though it would increase the need for monster detection (I assume detection is not influenced by the fact the monsters are invisible or not). This could be a problem for classes with little monster detection (all kind of warriors).
AerdanRunestar: That doesn't sound right; warriors should have decent monster detection. They're warriors.
Remuz: To detect effectively, warrior can either read scrolls, or pump magic-devices. I do not really like the second option (doesn't sound like warrior-ish to me), but this is currently the most effective one. The drawback with scrolls is that they come in a limited supply, while rods are not easily available. Right now it is not an issue, because, when having seen invisible, there is no need to detect monsters that are in line of sight, so detecting monsters is more-or-less optional. With that change, it would become mandatory at fairly low levels onwards (carrion crawlers, clear worm mass, anyone?), so we definitely need to either make scrolls of monster detection more common (mandatory storage in shops, and possibly cheaper), or rods of detect monster a much lower level item.
NeilStevens: We have so few binary things left. Can't we keep ONE? heh
DarkGod: Well player invisibility is already valued, it would make sense. Anyway I don't liek the way invis works now, it's hardcoded too deeply
NeilStevens: It would make sense if the player valued invisibility were implemented in a sensible way. I'd rather we make player invisibility binary, too, and just apply a see invisible flag to monsters that should have it.