Gemstone IV is an online text game developed by Simutronics Corporation, built using their proprietary Interactive Fiction Engine. Players connect to Gemstone using either Telnet or a third-party client, although Simutronics introduced their StormFront client in 2003. While enjoying a playerbase in the thousands in its early days, Gemstone IV has seen a rapid reduction in audience over the years, having fallen from the Top 20 MUDs on the popular MUD website, TopMudSites.
Gemstone IV uses a pay-to-play monthly subscription fee, and offers three different subscription models, but no free access. Simutronics introduced a third subscription model called GemStone IV - Shattered in May 2010, lifting previous restrictions on game rules such as PVP, adult language filters and introducing "unmoderated forums" for players who opt for a higher subscription fee than the normal.