Hmmsim is an indie freeware train driving simulation game developed and released by Jeminie for iOS and Android devices on July 28, 2014.
It allows players to drive a subway train through an unofficial virtual recreation of the Seoul Subway Line 2 metro line in the Korean city of Seoul, from Seongu Station to Samseong Station. Along for being the earliest-known Korean train driving simulator, it is notable for being the first mobile train driving simulator to support add-ons from BVE Trainsim.
It later received an updated paid sequel in 2015, titled Hmmsim 2, adding a new metro line while updating the graphics and gameplay options. It later received a reworked PC sequel in 2021, titled Hmmsim Metro.