SOLUTIONS FOR THE DOORWAY PROBLEM
Okay, as I see it there are two major approaches to solving the doorway problem. Either of these can be applied completely, or just partially. For example, the 2-wide hallway solution can still have a few one-tile hallways, and the monster/ability/trap approach is a gradual effect where it might need only a couple of these, or it might need 10 - we aren't sure.
The Map Gen Approach
This is a simpler approach to explain: it just means that we either eliminate, or drastically reduce the appearance of 1-tile width hallways in 100 Rogues.
Gameplay wise, this shouldn't have any negative effects on the gameplay, despite the fact that it's unusual for a roguelike (most RLs allow you to move diagonally, too!).
Graphically, Blake worries that this approach may end up making the levels look more stale since most of the maps will feel like rooms. In order to counter this, we might need to add more tile variation, and perhaps have two different types of "room-tiles" or something. Point being, a little work will have to go into making the levels look good with this approach, but I'm not too concerned about it (and of course good gameplay is more important than the levels looking believable). Blake recommends that we go with 2-width hallways being enforced, and being nearly as common as current hallways. I think this might work, but we might want to try that approach and a "no hallway" approach and see what plays best.
I tend to favor this approach because it is clean and elegant, and fixes problems without *adding anything* to the design.
The Other Approach
This one is definitely far more complex, but is more interesting. It entails adding more monster abilities, monster AI rules, traps, and possibly even more monster types if needed in order to attempt to solve the problem.
Here are some examples of monster abilities which would potentially help to solve the issue. No one of these alone would fix the game but having enough of them might do that.
Switch Spell - Monster casts it on you and switches position with you. Definitely would get the job done if this monster does it, but we'd have to be careful that they didn't do it repeatedly. Gypsies and Ghosts could have this spell.
Throw - Similar to the switch spell, this would be a melee range ability that some monsters could have where they throw you towards the middle of the room. I'm not sure which monsters could have this ability though, thematically, where it would make sense.
Duplication/spawners - A slime which duplicates or a spawner which spawns bats located near the center of the room MIGHT help, but if you have a secure position where you only have to fight one monster at a time, a Spawner could function as just an infinite experience machine. "Keep 'em Comin", our players might exclaim. So I'm not sure this solves the issue, as cool as they would be, but it might with the right application. Bats could spawn, Skybabies maybe... really anything could.
Evasive, Valuable monster - Perhaps there can be a non-fighting monster that you have to "catch" at melee distance, and who always runs away from you. This could be like a "trophy" system (similar to Skulltulas in Ocarina) that could have some kind of meta-game function. This might only help a LITTLE bit in terms of the problem we're talking about, but offers some meta-game that our game could really use (right now we have NONE).
Power Up - Perhaps some sort of ability where a monster, upon seeing you, begins some kind of powering up process making you want to rush him as fast as possible.
Pathfinding - Monsters need to be able to find their way around treasure chests and other monsters to get to the player. I'd say this is arguably a fix that needs to happen no matter what.
Defensive Melee - Melee monsters, if nearby ranged monsters, will stay close to the ranged monsters, realizing that they don't have to rush you. Perhaps only some would do this, some would be very aggressive no matter what. This would be smart tactically for monsters to do in most cases and would increase the effectiveness of both monsters.
Surround/spawn Trap - stepping on a tile would spawn 3-6 monsters around you (at least 3 tiles from you) in a circle (if possible). Might be tough to balance (ie, could be way too hard if it spawned 3-4 snipers), but might work.
Teleport Trap - stepping on a tile teleports you to a random location on the level. I like this one, it's natural and makes sense, and should be fairly easy to balance.
Jump Trap - throws you into the middle of a room, often found at doorways. Kinda a hacky little trap, not my favorite, but would definitely get the job done.
Overall, I tend to not favor this approach to the first one because it isn't as elegant, and I'm also not even sure that it will entirely fix the problem (although it may if done right). However I concede that right now the game is maybe a bit on the simple side, and we'd likely do well to incorporate a couple of these changes no matter what.
Can we do both?
Perhaps by doing a little from column A, a little from column B, we could get the best overall gaming experience. Reducing the 1-tile hallways to only being there like 20% of the time or so, and incorporating a couple traps and a new monster ability or two would probably get the job done.