Bungie has updated their site with a list of playable game-modes in Destiny. They have 5 game modes listed and a mystery mode that has yet to be revealed, although evidence points to it being “Raids” (Above).
Crucible (Competitive Multiplayer)
Enter the Crucible to hone your competitive skills against other Guardians in arenas that span the solar system. Victory will earn you rewards and reputation.
Explore (On-Demand Adventure)
Revisit the worlds you have discovered to aid the City in their exploration efforts, seek out valuable resources in order to upgrade your weapons and gear, and link up with other brave Guardians roaming the frontier in search of action and adventure.
Cruise around the surface of a planet in Fireteams of up to 3, taking odd jobs and tasks for the City. You can find minerals and resources out in the world that you’ll have some use for as you find weapons in Destiny that you want to stick with. This is a lower intensity activity.
Strike (Co-Operative Multiplayer)
Form a Fireteam, three Guardians strong. Infiltrate an enemy stronghold, cutting through wave after wave of enemy ranks emboldened by their fierce, battle-hardened leaders. Confront an enemy worthy of only the bravest Guardians.
3 player activities, with bosses and loot at the end. Their goal is a highly replayable activity that will – at higher levels – lead you into the loot game.
Tower (Third-Person Social Space)
Home of the Guardians, the Tower is a third person social hub where you can regroup, rearm, and form new alliances before venturing beyond the safety of the City’s walls.
Story (Epic Campaign)
Destiny features a rich, cinematic story, centered on your quest to discover and explore the remains of humanity’s Golden Age. As a Guardian, you must venture beyond our walls, into a wild and dangerous frontier, and take the fight to ancient evil forces hell bent on our destruction.
Soloable activities (you can still play them in groups of up to 3!), often with ties to the main story arc of Destiny (the campaign). These activities appear at various Levels (numerical, relative to the player) and choosing a higher level (relative to you) means you’re opting in for some additional challenge.
6 player, cooperative required, communication required gameplay. High challenge.