While cover is important, really it's all about line of sight. Luckily the NPCs don't ever 'look up' just like real people don't so you can always teleport onto a lamp post or a ledge and go on from there. Naturally there's also hidey holes, vents and holes in the wall, but let's look at the unique difficulties of teleportation.
Firstly, this game lends itself to the basic style of tabletop wargames which field individual units. If you have a lot of terrain, you could give the players a cut down ruler to represent the distance they can teleport and go with that. Unfortunately, since the odds of you having as many terrain pieces as the videogame has levels are quite small ... you will probably need to either make each level so ridiculously complicated that you can get a few hours of playtime from it or take another angle.
The other option is to keep it all to the imagination. Just like in a regular game where you can leap a certain distance, so you can do the same thing here - you just don't physically cross the intervening space. You might use floorplans and miniatures. You might not.
While this method can work to come up with some very unique outcomes, the game will either descend into more purist narrativism (player states they teleport onto a ledge above the cops thus there is a ledge there) or they scrutinise the GM's descriptions for phrases that indicate possible places to go (a more railroady narrativism).
Narrativism, you say? Why not just add in some dice?
You could do that. If you want to randomise the distance the player can actually travel, have a pass/fail system and then explain why they can't re-try the teleport and must instead sit on their bottoms or find somewhere else to go or have a pass/fail system where failure dumps them in plain view of everyone. While all of these work, none of them work well for a reliable system that fits in with Dishonored's style.
Don't worry. As always I have an answer for you. Make teleportation automatic. Give it a set distance. Then make the various places they can use more or less difficult. Imagine teleporting over a ledge and trying to hold onto it without slipping off and falling on your foes? Not as easy as it sounds. Make the players roll Athletics or Stealth or whatever to stay where they are quietly. If they fail, they start to fall and might even grab on (making noise) or teleport elsewhere. Or they hold their position but scare off a bird they didn't see or knock off some pebbles, drawing attention. The player must then select a new landing pad which may not be as beneficial. They might also need to roll a Perception check to ensure that the landing point can even take their weight.
|Anyone else get a few too many dodgy PCs?|
Floorplans are still a good idea in this, if you have a large enough table. Being able to move miniatures around to show their marching patterns. Demonstrating why certain pieces of terrain are more beneficial landing points then others (i.e. it's right above their head) and being able to model how people change their positions in response to sound are all good things.
This can be especially interesting for the players when they're dealing with 'Weepers' or other such twisted plague-bearing victims who might rush over to the lamp post and seeing them starting to bunch up could become quite an issue.
If there is more than one or two players, you should especially avoid making normal stealth checks for ducking around furniture or creeping along or else there's a very good chance that Stealth will stop being a viable option and the players will start storming places. Leave the stealth checks for the teleport landings and even then don't have it be a pass / fail. Have it be a pass / alert-oh-dear-best-teleport-away.
Anyway, a campaign based around Dishonored or including elements of it, should appeal to - you guessed it - Tacticians and Action Heroes the most.
Wow, a lot of videogames I've been translating have been good for those two groups which is unsurprising. What is surprising is how it's only been my recent of Game Translations that has shown such a bias towards those two groups.
Tacticians will love being able to find the perfect path across the terrain without getting spotted.
Action Heroes may be more prone to assassinations than simply passing unseen, though the adrenaline twitch of a good stealth scene interspersed with outrunning large robots or hordes of weepers should prove a good mix for most. Just be sure they have some patience. Dungeon crawlers and hack & slashers will find it dull..
Explorers will find the exotic yet familiar city of Dunwall to be quite interesting to them. It's so akin to our Victorian cities yet so different. Simply the cultural nuance and the descriptions will pique their interest, especially as they get to sneak into people's homes.
Investigators will likely the little hints and tips as to the grander conspiracy and may become very driven to prove their guilt. Give them the chance to piece it together and make a few physical handouts and you should be able to get them onboard.
Communicators will probably want to spend their time pitting the enemy against itself, driving in wedges, and raising internal paranoia. You could let them, just move it down an action-oriented route. If they steal this thing from this person, they will assume their nominal 'ally' did it.
If you want to check out the trailer, you can find it here. If you want to read up on the TV Tropes you can find them here.