Boom is a freeware audio player for the Windows platform, by the developer of foobar2000. It is aimed to be a portable (i.e. install-free) easy-to-use player with few advanced features.
The player offers gapless playback of "a variety of popular audio formats, including: MP3, Ogg Vorbis, FLAC, Musepack (MPC), WavPack, WAV, AIFF, MP4/M4A, WMA". It is ReplayGain aware, but does not do ReplayGain scanning.
For tagging, a simplified version of foobar2000's file property box is available.
Unlike foobar2000, it has language support.