Omega is an old roguelike computer game for Unix; it dates from the 1980s. Omega was intended to be a very difficult game, where a new player will die quickly unless that player knows what to do. Players probably want to have experience with the keyboard controls of other roguelike games before playing Omega.
Though some players have enjoyed Omega, other players have found it to be too cumbersome, notwithstanding the game's difficulty. For example, in most other roguelike games, to pick up an item from the floor is a one-key operation. (Presumably, you carry a pack to store your items in.) However, in Omega, this item goes "up in the air" while you decide which body part to carry it with.
In contrast to the games Rogue or NetHack, where players can start exploring the dungeon immediately, or Angband, where players need do only some shopping and equipping before entering the dungeon, Omega requires players to do some additional preparation at the start of each game. A new player will want to join a guild, and that can only happen if the player changes their alignment from neutral to either slightly lawful or slightly chaotic. The least-experienced players will make a small donation to an orphanage (in the game) to become slightly lawful, then join the Paladins. This is only because it is easy to become very wounded during the first steps of your adventure, but you can retreat to the Paladins who will always offer to heal their members.