Classic Rogue is described as 'Updated version of Rogue with modern graphics and sound'. There are more than 10 games similar to Classic Rogue for a variety of platforms, including Windows, Linux, Mac, Android and iPhone. The best alternative is Dungeon Crawl Stone Soup, which is both free and Open Source. Other Classic Rogue like games are NetHack (Free, Open Source), Brogue (Free, Open Source), Rogue (Free) and POWDER (Free, Open Source).
Dungeon Crawl Stone Soup is an open-source, single-player, role-playing roguelike game of exploration and treasure-hunting in dungeons filled with dangerous and unfriendly monsters in a quest to rescue the mystifyingly fabulous Orb of Zot.