Super-truite released an updated version of the ArmAGeddon gamemode and at the same time the ArmAGeddon addon by him and Make Love Not War on the BI forums.

Quote :
ArmAGeddon is a Coop Multiplayer game mode.
You have to flee Altis while the island is sinking!
CSAT forces are fleeing as well and you have to try to steal a vehicle to escape. Tornadoes, earthquakes, meteor falls etc. will spice up your journey!

Typical game:
* you spawn with few ammos, even sometimes with no weapons, no map ect.
* Find equipment left by retreating CSAT forces in the buildings or try to eleiminate the CSAT's which are left to get their gear.
* Try to find a chopper quickly (remember the water level is rising). Either follow discretly CSAT's (they are likely to call for an extraction) or
find a abandoned one (usually those have no fuel or need to be repaired (Repair tool kits and fuel canisters can be found in buildings if you are lucky)

Tip:
Try tweaking your graphical options to be able to have the particle effects at least in 'high'. You will have better tornadoes, meteors ect.
Also, there are two new options for particle effects: "Ultra" and "Armageddon".

Changelog:
• Addon changelog version 1.1:
  - added new sound effects
• Mission Change log version 1.15:
  - fixed: Tornado Particle effect radius was too small sometimes
  - fixed: sound of thunder was not playing
  - fixed: the ghosthawk is now locked
  - added: Sync of the tide level across network
  - tweaked: number of abandonned choppers increased
  - tweaked: respawn is now closer to the group
  - tweaked: engines of abandonned vehicles are less likely to be destroyed
  - Fixed: respawn parameter issue
  - Fixed: Refuel with fuel cannisters is now working
  - Fixed: Respawn marker now invisible
  - Sync of tide is now a parameter for server admin