As Magnus explained, NetEpic has its roots in second edition Space Marine which was derived from first edition Space Marine, which was preceded by Adeptus Titanicus in the late 1980s. Epic goes back a very long way as you can see

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Space Marine (both versions) was very popular, and a lot of people did not like the radical shift from Titan Legions (the third edition of Space Marine) to Epic 40K. As a result, the Epic community split into two groups. One group opted to revise and update the old Space Marine rules (this is what is now known as Net Epic Gold), while the other played Epic 40K, its successor Epic Armageddon, and then took over rules development once GW pulled the plug on supporting Epic (this is what is now known as NetEA).
Having played both games, I feel that NetEpic is the better game if you like the diversity of the Space Marine era, while NetEA is better if you like a more 'realistic' approach to combat with concepts such as unit suppression. Both games have superior rules to GW's 40K and Fantasy (now Age of Sigmar) lines.
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SoƱando con una playa donde brilla el sol, un arco iris ilumina el cielo, y el mar espejea iridescentemente.