Zombies won't follow player up/down stairs.

[Myobu1]

Describe the bug

I'm currently using build 9651 with experimental Z-levels enabled. I've had zombies in hot pursuit a mere step away only to get to complete safety the moment I use some stairs. They do not come into the basement, nor will any creatures in the basement venture above ground.

Steps To Reproduce

Steps to reproduce the behavior:

1. Have a zombie(s) stand on/close to some stairs ready to maul you to death.
2. Go up/down some stairs.
3. Enjoy complete safety and escape from your pursuers.

Expected behavior

Previously, zombies/creatures used to follow the player into a basement. Now they do not. Zombies should follow the player down/up stairs, especially if the zombies saw the player go into a basement.

Versions and configuration

• OS: Windows
  • OS Version: 10.0 1809
• Game Version: 0.D-7798-g2da3f5e [64-bit]
• Graphics Version: Tiles
• Mods loaded: [
  Dark Days Ahead [dda],
  Disable NPC Needs [no_npc_food],
  [DP_MOD] No Highlight [DP_No_Highlight],
  [DP_MOD] Indicators: Chesthole [DP_AMAZING_CHEST_INDICATORS],
  [DP_MOD] Hide STATUS [DP_No_Status_Tiles],
  No Flaming Weapons [no_flaming_weapons]
  ]

Additional context

I'll post my save file just in case it's needed. I've positioned my character to be standing on some stairs with a murderous horde of zombies on every side.

save.zip

[KorGgenT]

this is known, and partially due to the fact that stairs do not align. I don't know if there's a copy of this issue anywhere, though.

[stk2008]

The main issue I would say is monsters teleporting down into the basement.

Would this also be related some how?

[DanteTorn]

This has been pretty annoying for me in conjunction with experimental Z-levels causing creatures to block stairwells but never moving off of them to allow you to pass. Turning off experimental Z-levels, reloading, and then moving through the stairwell "fixes" this though.

[Aloxaf]

@DanteTorn Another solution: #34005 - Beat the bug with another bug

[inverimus]

This is also a problem with ramps now. You can avoid hordes of zombies just by going up a ramp from 1 tile away and you are perfectly safe there.

[Night-Pryanik]

Tested on latest experimental as of April 11, 2021. Zombies followed me both downstairs and up on the ramp.
Closing until reconfirmed.

[alexandertoresson]

On latest experimental as of today, zombies won't follow me down stairs in a subway, even with experimental z-vision turned on.

[alexandertoresson]

Maybe it's related to alignment of stairs? If I stand on the stairs and peek up, I see the right tile with the stairs on the level above. However if I the press > to look down at the tile I'm standing on, another tile than the one I'm looking at will be highlighted.