The idea is to take away visibility from rooms that your script cannot see. No longer would you be able to just look at the map and know what your script cannot know, letting you essentially bypass the visibility rules with direct commands and manually placed flags. If possible, in this world, even terrain should be hidden in non-visible rooms.
For an extra challenge, a second rule could be to no longer show usernames of unfriendly creeps and structures. I think this would neatly eliminate any form of allied play, and bring some interesting strategic puzzles to consider.
Spawning new into a shard with these rules should be handled a bit differently. Instead of allowing a player to select a room on the map, a short list of rooms should be randomly selected for the player to choose from, showing the terrain, source, mineral, controller as usual. If the player finds these choices unsuitable, he can request that the server re-roll a new set of suitable starting rooms after a brief cooldown time (30 seconds or so).
Admittedly, this would also break any concept of spectating on this shard, but I think the individual challenge in such a world could be refreshing for some players. Of course, this is a major world rule, and I wouldn't want to break what already exists. This is proposed merely as a possible set of rules for an alternative shard. Those who find these rules unappealing, are free to play on other shards.