The player chooses a scenario, difficulty level, and a character. The difficulty level is tied to what enemies and items the player encounters as they progress through the scenario. The game has five scenarios, each of which has an event checklist consisting of special actions that the player must perform to reach 100% completion. Upon doing so the player will unlock "Infinity Mode" in which all the player's weapons never break or run out of ammunition.
Each scenario also has "SP" items. These are invisible items hidden throughout the level, and are randomly generated on two paths. There are twenty scenario items for each scenario, and twenty items specific to each character hidden across the five scenarios. If acquired, these items unlock new costumes and the option to listen to their ad-libs.
Players could connect to the internet servers using a broadband connection and a network adapter. Account registration and login were required. Once players connected and logged in, they could then choose between Free Mode and Scenario Mode. Free Mode took place in a lobby and allowed players to create their own games, scenarios, and difficulty level. Scenario Mode would choose the scenario and players automatically. When a player first started online, they would begin on the Outbreak scenario and progress from there. If the player wished to stop playing, they could save their data and start off from the scenario they were up to at the time. If the player had beaten a scenario, they acquired a star by their name.
On December 31, 2007, Capcom shut down the US servers for Outbreak and on June 30, 2011 for the JP servers.