Angband is a text Dungeon adventure RPG type of game, similar to Nethack.
Note: Angband isn't very easy to play on BE: displayed characters are very tiny and you need to control your hero by hitting tiny cursor keys on screen with your stylus.
Getting it to work on BE is not straightforward, so listen up: first of all, you need to unarchive the .cab file you downloaded. The author messed up and packaged the cab inside of another cab. This means that you need to unarchive it first using a program like Filzip or Winzip.
Simply right-click on the cab and choose Filzip -> Extract from the menu; when you're done with that, copy the resulting .cab file to your BE.
Now that you have it on your BE, double click it and choose the location to install it, for example Storage Card/Program files. It will complain that there's not enough space in that directory, and will ask you whether you want to pick a different location; click No. You're done, it's installed now.
Once you're in the game, make sure you change to landscape mode in options / graphics. This will make the game a little easier. Holding and dragging screen will move it around. Unlike with Nethack, there are no graphic tiles and there is no way to move around using stylus, you're pretty much stuck with on-screen cursor keys which are rather hard to hit.
It's difficult to use stores because prices and descriptions don't fit on the same screen, even if you're in landscape mode. All in all, this game is much harder to play than Nethack.