Way of the exploding fist was the original c64 karate combat game in '85
Fist II the legend continues was a "karate adventure" along the lines of karateka but much bigger and less linear. but sadly quite buggy.
Fist+ was a kneejerk reaction to IK+. basically 3 player fist. it was lacking in polish looked like what it was, an attempt to cash in on IK+ using the old exploding fist name.
as to IK vs Fist, this one still rages on any c64 forum that asks the question. opinion is fairly evenly divided. my own personal opinion is that IK was "fluff" all flash and lacking in substance. it was faster than Fist, BUT Fist was made to be slower. IK tends to be played by thrashing the joystick around till one of you falls over and blocking is haphazard at best. Fist however gives you time to react to a move as it animates and blocking is executed flawlessly.
watching 2 fist "masters" at play is like watching a real fight. waiting , attacking, defending, countering.
for my own opinion, 25 years after its release its still the best 2 player fighting game on a computer for fun. i was involved with doing a conversion of this to amiga and PC which sadly never got finished. it's my "thing"