Restrict auto-travel to avoid exploration

[Nekoatl]

In the interest of not rewarding tedious gameplay patterns, I propose to modify the auto-travel (not auto-explore!) algorithm to only traverse tiles that do not reveal/explore any new tiles. There are a few factors that combine to currently advantage manually travelling to the nearest up-staircase while being careful not to step on a tile which has line-of-sight to an unexplored tile.

* It's much safer to rest and recover on a fully explored level than on a partially explored level. So, whenever a character has their HP/MP significantly reduced, it's advantageous to retreat to the previous floor while minimizing the risk of revealing new monsters.

* Traps are significantly more dangerous for injured/exhausted characters, so it's especially important to avoid triggering traps when your character is in need of rest.

* Exploring tiles carries an increased risk of revealing new monsters and is infinitely more likely to trigger random traps.

Since manual travel is naturally more tedious than auto-travel (even more so if players have to think about which tiles have line-of-sight to unexplored tiles), this constitutes an advantage to tedious gameplay which could be reduced by modifying the algorithm, as that would significantly mitigate the risks of using auto-travel to retreat to safety.

[bel]

Auto-travel is just an interface feature. I imagine there wouldn't be any problems in creating your proposed feature in-game, which can be toggled via an rcfile setting. Like there's an rcfile setting for making autoexplore explore near walls.

As for the proposal itself, it's not clear to me that auto-traveling to avoid exploring new tiles is always the best option. Sometimes you may want to take a little bit of extra risk in exploring new tiles, in exchange for getting to your destination faster (an outcome which may mean less risk).

However, you are probably right that, in general, you want to avoid revealing new tiles. So by default auto-travel shouldn't reveal new tiles. So there could be an rcfile setting for "travel via shortest path".

[Nekoatl]

I tried to use explore_wall_bias to get the auto-explore to stop ignoring the nooks and crannies on the edges of cavern-type levels because the default behavior wastes a lot of turns by leaving them to the end and then going all the way around the level in a final pass. Sadly, I didn't find a value that would get this to work.