There was never really any doubt over whether or not Eugene would have been a big gamer prior to the apocalypse (remember when he asked Tara what type of games she prefered to play way back in Season 4?), but this week, along with playing actual video games, he also made a subtle nod to the fact he was a Dungeons and Dragons fan before the outbreak.
For those uninitiated into the world of Dungeons and Dragons, before you start playing, each player must create a character and each character must be categorized into one of nine alignments which set out how a character should behave in the game. Here are the nine alignments (complete with a fair representation of their corresponding Walking Dead characters):
Now that you understand alignments, I'm sure you can appreciate Eugene's comment to Negan's wives when he said "truth of the matter is, I'm not good. I'm not lawful, neutral, or chaotic — none of the above."
By the end of the episode we saw that Eugene definitely didn't fit in any "good" alignment when he was quick to claim "I'm Negan" in the presence of the Big Bad himself. Instead he actually demonstrated that he would probably better fit as a true neutral, doing what he thinks seems like a good idea. Obviously he still realizes that it would be better to have a good ruler than an evil one, but isn't really committed to upholding good, and is more concerned with his own survival.