Countdown Mode is a game mode in Resident Evil: Revelations 2. It must be unlocked for each episode individually by simply completing the episode, and it can be purchased for 1000 BP per episode in the Rewards menu.
In this mode, there is a timer constantly counting down. The time limit can be extended by destroying the hourglasses found throughout each stage and by defeating enemies. If the timer runs out, the game will automatically end.
All episodes have a pre-determined starting loadout for both characters and the Workstation cannot be accessed while in this mode, this means no Custom Part or special weapon can be equipped. Additionally, any inventory progress will not save in-between episodes, so if ammo is picked up in one episode, it will not show up in the other and will instead be replaced by the pre-determined starting loadout.
Below is a list displaying what each character starts with in every episode, this same loadout is also used in the Invisible Mode: