Air Dash & Leap System

A full 3D mobility overhaul for Left 4 Dead 2: air dashing, chained high jumps, wall-running, grappling, sprint mode, and two bullet-time modes — all tuned for co-op and stable under sustained fire.

Mobility

• [ ]Double-tap a direction to dash on the ground (10 stamina); press Shift in the air to air-dash (25 stamina)
• [ ]Chain high jumps (35 stamina each) for extra height; steer freely with the mouse mid-air
• [ ]Hold W against a wall to wall-run: look up to climb, W + strafe to lock height and shoot freely, Space to leap toward your crosshair (+50 stamina)
• [ ]Ledge rescue — grab a ledge while falling and pull yourself up
• Fall protection: any fall is safely absorbed while stamina is above 25

Grappling Hook

• [ ]Press Alt1 to fire: a tap pulls you in quickly (15 stamina); a long hold pulls to the target and auto-hangs (25 total)
• [ ]Cannot pull below 50 units of ground clearance, cannot hang below 80 — prevents low-altitude spam
• [ ]Hanging: rises at 20 u/s to hold height, drains only 1 stamina/sec; headshot kills on Special Infected restore 25 stamina
• [ ]While hanging: W checks for a wall ahead to enter wall-run (+160 starting speed); S+Space wall-jumps into air bullet-time; Alt1 detaches; Shift detaches and air-dashes
• High-jumping mid-pull does not cancel the pull — your vertical velocity is preserved
• Console command:`bind mouse5 +alt1` (mouse forward side button)

Sprint (Overdrive) Mode

• [ ]Toggle with Shift; speed scales with health: 1.10x at low HP, up to 1.35x at full
• [ ]20-segment stamina bar (max 100); regen starts after 2s standing, ramps to 2x rate over 3s
• Adrenaline no longer negates drain — instead restores 20 stamina/sec in the air and on the ground, enabling aggressive combos while still managing the bar

Bullet Time

• [ ]Air Bullet Time: S+Space during a wall-run triggers a slow-mo dash-jump (25% speed), or Shift during a parallel run for slow-mo aiming. Each Special Infected kill adds 1s (max +2s) and grants a free stamina high-jump. Ends on air-dash or landing.
• [ ]Ground Bullet Time (Killing Time):Shared team charge fills at 20 — Common +1, Special +4, headshot x3. While sprinting, the trigger gains: no-reload magazines (drawn from reserve), +70 melee range (one-shots Commons; 250 dmg per hit on Specials/Tank/Witch), +25 stamina and +5 HP per melee kill on Special/Tank/Witch
• [ ]Headshot Chain: Land a firearm headshot on a Special (or enough Common headshots), then switch to a secondary within 1.5s: melee ignites a 500-unit fire sea; pistols heal nearby teammates +15 HP and revive downed ones (preserving black-and-white)
• [ ]Air stomp hover: bounce high off a Common's head during bullet time; each headshot while hovering extends the hover and restores stamina

Performance & Stability

• [ ]Shells are periodically cleaned up during bullet time to prevent ED_Alloc errors from sustained fire
• [ ]Fire sea visuals optimized to limit entity count
• Low-priority HUD hints are throttled during bullet time

Other Details

• [ ]Kill stamina: Common +5 / headshot +10 / Special +20 / Special headshot +50
• [ ]Teammates get 50% speed compensation during bullet time
• [ ]Full team invulnerability during air bullet time
• [ ]12° view tilt (shared by wall-run and hanging)
• [ ]All values are written to an auto-generated config and persist across map changes
• [ ]Trilingual: Simplified Chinese, Traditional Chinese, English
• Chat commands: !bt toggles bullet time, !cc toggles color filter

Compatible with all official campaigns and most third-party maps. Supports single-player, listen servers, and local co-op.