Gekkeiju Online™ has a very entertaining Skirmish-system that allows players to explore challenging instance-based dungeons and encounters. The Skirmish-instances also scale up based on players' level so they'll always offer a good challenge.
Skirmishes are unlocked by completing certain Quest-chains in the game. After unlocking a Skirmish, the player can enter it by just talking to the NPC who offers the Skirmish-Quest.
Another way of getting into Skirmishes is to be in a party with some other player who has already unlocked the Skirmish. This allows anyone in the party to enter it.
Skirmish-instances are mostly meant for parties as they may contain even some hard Boss-monsters. However, some instances may be soloable as well.
While Skirmish-instances are relatively challenging, they are still easier than Raid-instances.
Skirmishes have different kinds of rewards depending on the Skirmish-quest and its hardness. The higher the Skirmish's level the higher the rewards will be.
The common rewards for Skirmishes are money and Skirmish Points. However, some Boss-monsters in Skirmish-instances may also sometimes drop rare equipment.
Skirmish Points are point rewards from Skirmish-instances. They can be traded into various valuable items and equipment at Skirmish Vendor-NPCs.