Angband
Angband is a computer game that were originally played on DOS (although variations have been released that can be played on Windows) that featured @ as your avatar fighting against various letters, numbers and symbols, picking up potions, weapons, spells, armour and other pieces of equipment as you go down different levels of a dungeon. Angband is based on Rogue, which in turn is based on Lord of the Rings. The later computer game Diablo I is similar in concept to Angband, although the creators of Diablo do not credit Angband for its creation.
In Angband, you start off with a weapon (depending on your class), perhaps some armour, perhaps a spell book (depending on your class), a number of wooden torches and some rations of food, in addition to some money, up to 100 coins. You can then go to shops and buy and sell things before you head down into the dungeon. As you go, you pick up things, dig through walls, until you find an exit down. > means a staircase down, while < means a staircase up. You also fight creatures and can gain experience to gain levels.
Different variations of Angband have been released, called Fangband, Zangband (the most popular variant), Multiband and other names. Whilst it was originally made for DOS, later versions can be played on all versions of Windows. It can be downloaded free to use.
One criticism of Angband is that if you die, that's it, and you have to start all over again from the start. There are no extra lives or anything like that. With some variations of the game, on dying you could shut down the game and then not have died, but in later variations that option isn't possible.