Challenge Mode is a game mode in Overload where a single player tries to survive against an unending stream of Autonomous Operators and score as many points as possible by destroying them. It has two variants: Infinite, which ends when the player is killed; and Countdown, which adds a 5 minute time limit.
Challenge Mode can be played in the following (official) levels:
All weapons start with Plus upgrades in Challenge Mode. Further upgrades are awarded every 25 kills in Infinite, or every 20 kills in Countdown. Awarded upgrades alternate between secondary weapon upgrades and primary weapon upgrades. The first upgrade is always for a secondary weapon.
When an upgrade is earned, it is applied to the currently selected weapon. If that weapon is already upgraded, then a random weapon of the same type (primary or secondary) is upgraded instead. The upgrade chosen for that weapon is also random, but can be toggled manually using the Hologuide key for a period of 10 seconds after receiving the upgrade.
Furthermore, when a weapon is upgraded, its ammo is refilled.
A few special events can happen during a Challenge Mode session:
Twitch Tournaments are a Twitch extension that allow streamers to setup private/public challenges.
Players that want to participate need to link their overload player to a twitch account to be displayed on the leaderboard.
Due to the bug that the extension doesnt differentiate between countdown and infinite runs, tournaments normally get set to infinite.