Warband runs on a very old engine, making it playable on low-end laptops (such as Intel integrated graphics chips). Users with these machines are often students or younger gamers who may not have the disposable income to purchase the game on platforms like Steam, turning them toward piracy.
Once decompressed, the game runs exactly like the retail version. The compression happens during download; the files are fully restored on your hard drive. There is no FPS drop, no texture pop-in, and no audio lag. mount and blade warband highly compressed top