FallWarn

FallWarn is a lightweight client-side mod that highlights the block selection outline in red whenever breaking the block you're currently looking at would cause you to fall.

FEATURES

• Red outline warning: the vanilla block selection outline turns red when breaking that block would cause you to fall
• Real support simulation: FallWarn checks your full footprint and simulates what happens if the targeted block is removed, rather than just checking for air underneath you
• Toggle keybind: press the ] key to enable or disable the warning at any time (fully rebindable from Controls > Key Binds)
• Configurable fall threshold: choose how much of a drop counts as "risky," from any fall at all to only drops that would actually deal fall damage
• Optional Mod Menu integration: if Mod Menu is installed, you get a small config screen to adjust the threshold - Mod Menu is not required to use FallWarn

HOW IT WORKS

FallWarn doesn't just check whether there's air below the block you're looking at. Every tick, it scans your player's footprint, works out which blocks are actually supporting you, and simulates what the world looks like if the targeted block is removed. If no other support remains and the resulting drop clears your configured threshold, the outline turns red. Lava below you is always flagged as risky, regardless of the fall distance.

NOTES

• This mod is 100% client-side. It does not need to be installed on the server, and it's safe to use on servers that don't have it.
• The default fall threshold is set just above the point where fall damage starts, but you can lower it to catch every single fall or raise it to only flag serious drops.
• Mod Menu support is entirely optional. FallWarn works exactly the same with or without it installed; the config file can also be edited by hand if you prefer.
• You are welcome to include FallWarn in modpacks.