Valkyr is a game developed by Colin Dooley and published by Gremlin Graphics.
The game pays tribute to early space shooting arcade games such as Galaga, Moon Landing, Phoenix, etc. and features several speech samples using 4-bit logarithmic PCM.
The original samples sounded a bit harsh due to its bad quality. This version uses a new set of voices generated from scratch by modern means and still uses the PSG chip to play them.
Also, the starting melody (an excerpt from Wagner's "Ride of the Valkyries") has been corrected (it had some wrong notes) and the loading routines have been modified to make the game compatible with 32K machines.