Hi, enemies with ECM can scramble the rockets which then select a random new 
target. This behavior is consistent with the original. The difference is the 
probability of the scrambling:

anti-ecm \ ecm  0    1     2
0              100%  15%   0%
1              100%  50%   15%
2              100%  85%   50%

I'll put this table into the game guide.

Could you please explain that table? The behavior I am facing now, is I am 
playing the campaign and about done defeating the Garthog planets. I send 3 
battleships to each planet and shoot missiles/bombs at the space stations and 
plasma projectors. I fire volleys of 6, and I find that most of the time 1 or 2 
of the rockets will hit the space station and the rest will find new targets 
(primarily my expensive flagships). I do not have ECM or anit-ECM available to 
me.

Does this seem like the expected behavior?

At that stage, you have 15% chance of hitting the space stations (Rocket 1 
Anti-ECM=0, Station ECM=1). This is the expected behavior. Rockets are much 
better against small and medium ships in general.

However, I have little information about the original, i.e., whether Garthog 
Space Station 1s should have Anti-ECM=1 at all. Another question is whether to 
allow ping-pong like rocket bounces between two Anti-ECM wearing units. 
(Norbert?)

OK, well either I am simply not good at playing this game, but I believe this 
is more an issue where some balance is needed. I am attempting to play the game 
on easy because normal was just too annoying (repeated a lot of missions a few 
times). Is the same table used all difficult levels? I feel 15% is simply too 
low.

I do not know if Garthog Space Station 1 has ECM or not, however I doubt they 
had ECM simply because the Garthos were a very weak race in the original game, 
they don't use shields and all their ships had low firepower. I can attempt to 
setup the real game in dosbox and play through it, but that would take a long 
time, and I hope the information is available somewhere.

The table applies to all difficulty levels. I sometimes get feedback about 
difficulty, but players mostly find it too easy. Level 1-2 missions are pretty 
much straightforward and easy, unless you run out of time due high speed 
settings.

Most quantitative information is missing from the original. We had a similar 
issue a few months back and some users took the time to check out things, hence 
the table with approximations. DOS IG rarely works for me so I have to rely on 
other testers. The only known property so far are the ship firepowers, but 
neither the firing speed nor the hitpoints are known.

I've updated the hit probabilities table to include a difficulty level and 
backfire probabilities. I've increased the hit probabilities for easy and 
normal and set the backfire probability to %25 and %50 respectively