Regnum Online is a free to play MMORPG that combines PvE and PvP with a unique realm system that allows players to progress through difficulty as they level up through the game. The first realm players are able to explore are relatively safe. It uses the familiar questing hub system where players explore towns to unlock new quests and progress through the story. The Inner Realm is a more dangerous zone that is home to more difficult quests and monsters. This area is best suited for parties and groups of players, but solo players can also choose to face the challenges in the Inner Realm. The War Zone is the ultimate challenge for skilled players. Once you're ready you can head deep into The War Zone for intense PvP where three realms clash together in an endless war. Join a clan and defend the castles and forts to earn rewards for your realm.

To compliment the realm difficulties the game uses a familiar color system to gauge the difficulty of enemies. Players can better gauge the strength of their enemies by checking the color tag displayed next to the monsters name. Grey represents minimal challenge while higher colors like Red and Purple mean the monster will most likely kill you if you attack it alone.

Players are able to choose to play as one of three classes Warrior, Archer and Mage. Each class follows typical MMORPG progression mechanics where players earn experience points and gold through completing quests, defeating monsters and winning PvP battles. Players can also customize and strengthen their characters with a huge selection of powerful items including highly detailed sets of armor and some devastatingly powerful weapons.