Bug: Scout Bombing - Remotely alerting scouts with player's past positions

[fleet sedge]

This is a bug that makes it possible for scouts to be alerted by having their feelers trigger on a player's past position. It can happen to any scout on any level, as long as there is a door close enough to the scout to set up the bug. While not exclusive to that level, this bug is infamously common on R7E1 - likely because the level's design strongly incentivises the players to play in such a way that the bug is set up.

Steps to reproduce

This bug can be set up with two players (Player 1 and Player 2), and a scout with a closable door leading into its room.

1. Have Player 1 move up to the door to the scout's room (but not enter the room).
2. Close the door.
3. Have Player 1 move three or more rooms away from the scout.
4. Open the door.

It is now possible for the scout to be alerted by passing its feelers through Player 1's past position from Step 1.

This video showcases the bug: https://youtu.be/LHGtqTBGG2U

Additional information

Player 2 is only required so that there is a player close enough to the scout so that it will extend its feelers. Player 2 can stay outside of the scout's room or stay inside it, they can move three rooms away and then return, and it will still be possible for the scout to be alerted.

• Notably, since Player 2 is allowed to stay inside the scout's room the entire time, this bug is not related to the scout going inactive due to having no accessible players.

Player 1 can go down after Step 3, and the scout can still trigger on their past position, however, Player 1 will need to be revived before the scout becomes alerted. This differs from the scout's 'normal' behavior when its feelers trigger on a downed player, in which they can trigger on a downed player, but the player must be revived and then be within range of the scout's room before the scout will be alerted.

• This indicates that while the scout is storing the player's past position, it still checks the player's state (alive/downed).

This bug does not require the relevant door to be adjacent to the scout's room. The door can be one room away and still be used to set up the bug.

If a scout has the bug set up, but then dies and respawns, the respawned scout will not have the bug set up and will not be able to trigger on the player's past position.

Thanks to @graceful roost for spearheading the bug hunting. Also thanks to @little quest, @tacit iris and @grizzled yarrow for help during testing.

Potential Fix

The current behavior is due to the fact that the scout stops updating the player's position when they are inaccessible or out of range. A simple fix could involve just forcing active scouts to update the positions of all players regardless of if they are accessible.

This is of course unsolicited advice, and I trust the dev team to find the best way to fix the behavior.

@weak isle I would be honored if you could take a peek and pass it along to the rest of the team.

[weak isle]

I will 🙂

[fleet sedge]

@glad pendant We made a thread for this here

[glad pendant]

I don't really have anything to add, the description you have provided is ample and mod I made for the fix implements what you have suggested 👍 - you guys already did a great job investigating the issue !