Alignments
Every living thing in Sumu has an alignment from the range of Demonic to Angelic. Some guilds have alignment restrictions and the effect of spells might change as Alignment changes. Alignments are especially important to the members of Priest guilds.

Communications
Discussion channels are used for discussion of various topics. Players can create their own channels and mark them private if they want to limit the audience to their own set of people. The news system has several different discussion areas where changes to the game are usually announced, they can also be used by players to discuss various things in more detail than the channel system allows.

Death
Death is a horrible happening, unwanted for sure. When a player dies, he is transformed into ghost. Equipment will be also moved to the ghost. Player can ask for resurrection from a priest of his/her align, or pray in the church. Resurrection won't take as much experience as praying would. Being dead is also the only way to get reincarnated.

Events
Events are special happenings started by a daemon or a wizard. Events usually affect the whole mud, or sometimes players can choose whether or not to participate in an event, such as snow ball war or blood bath.

Experience levels
Experiece points are gained mainly from killing monsters. Every monster has a value of some experience, and when player or a party kills that monster, the experience is awared to the killers depending on their levels. Players can use experience to advance experience levels or guild levels, or train/study in a guild, there are also some unknown magical means which use experience.

Guilds
There is a number of different guilds in Sumu, each guild has its own unique skills and spells. The choice of guilds customizes the player further.

Outworld
The virtual outworld contains about 250000 rooms, many diffrent terrain types, many animals and monsters depending on the terrain type. Areas and special places are connected to the world and each other through the outworld.

Party system
Players can form their own parties, lead by one player. With a party players can usually get experience with better rate than by soloing. Sometimes a monster is so tough no player could kill it alone, but have to have an organized party with tanks, healers and damage doers to slay it.

Player killing
Killing players is generally allowed, as long as the killer has a reason for it. Massmurdering newbies or innocent players is frowned upon by the gods.

Races
There are many different races in Sumu. Each race has its own base statistics, size, special abilities, allergies and experience gaining rate.

Reincarnation
A player can change his or her race and guild by reincarnating. The reincarnation allows the player to re-select his or her race and guild, and re-spend the previously gained experience points, minus a slight tax, on new spells and skills.

Saveable Equipment
Whenever player quits, all of the equipment carried by him or her is dropped to the ground. Player can save his/her equipment in a rental locker, or in player customizable castles, which are placed in the outworld.