No wards, MASSIVE, reduced vision, no minimap (I dunno how tremor sense would work here), etc. Pretty similar to a noc ult. I really don't know how it would work but i'd love some sort of huge maze map where you never know where your enemy is and stuff. While it would lack strategy and stuff like that it would be really fun imo. Maybe it could even be a all-on all and not a team match.
EDIT: And my "gamemode" i mean map.
I've thought this could be a really fun idea for a while now, especially if it was a randomized maze.
My personal brainstorming:
This game mode would be far more objective focused than ye normal League of Legends.
The good news, it needs a whole new map, and could be a nice addition to the game as we have it. It would be a very unique addition to the MOBA genre.
The bad news, if not implemented correctly said gamemode would become the next Dominion.
Objectives would be centered around helping you find the enemy team and eliminate them.
Have certain alters that when captured activate a series of orbs to light up and give your team vision of a certain part of the map.
Have other objectives that once obtained show you the path to take through the maze to find the nearest enemy.
Have an objective that locks out enemy respawns. Maybe one per team (so you have to defend yours and capture the enemies) or maybe one per map (whoever holds it is in the stronger position). The game can be won by eliminating all enemies. Re-enabling respawn instantly respawns all dead allies.
With the above, there would need to be a mechanic to prevent a lone person or two from just never being found and stalling out the game by never being found/caught. This could be a point system, a "no kills were had in X time, game over", or similar.
To prevent "the most mobile team can ignore the entire maze and just dash over the walls", only certain walls would be dashable.
To keep it fair for our immobile friends, some walls could be "climbable" (think scaling a vine covered wall), where they can slowly move past the wall as oppose to finding a way around.
To prevent Rek'Sai being a mandatory pick-ban, limit her tremor sense so it can't sense over walls. If a hallway turns, Rek'Sai can still use tremor sense to know what's around the corner.
Have hostile PvE elements. You turn a corner, a monster sees you and starts attacking. This could help with keeping things interesting while teams are trying to find each other.
Special buffs for random encounters?
The maze could be shifting. For the first 5 minutes it's configured one way, then all the walls rearrange into a new configuration
I'm sure there are more ways this idea could be expanded on, but these are things I've been thinking about for a while.
http://img594.imageshack.us/img594/8095/cm2920905091a774e1008.gif
Would really love this mode to be implemented, plus, if they make a map for this, it could be used as an alternate map for the custom Hide and Seek game mode.
Who needs a map?
Picks 
I have thought about this a lot too. I think that the best enviorment for this map would be the Zaun sewers. not only that like the vision pillars on the ARAM map where whichever team takes them gets vision. I think instead it would be good to have traps or environmental hazards.
