Introduction

I am a software developer and I've been with my current company for about 4 months now. Initially I've generally stuck to myself but after a while (a month?) of getting to know everybody I've started spending most of my break time with a group of colleagues who share similar interests, mostly board and RPG games. To give some background as to how close we were, we generally ate lunch together, spent most of our extra break time chatting about random stuff etc. We also met once or twice after work to play board games and share a beer.

The RPG session

About three weeks ago they started talking about their RPG (D&D) session (which started before I joined the company) and since they saw that I was clearly interested, I was invited to join them. To my knowledge, the campaign was about three sessions in and I was one of the three new people who would be joining (for the total of 7 players). After about and hour spent creating our new characters we started actually playing. After some generic role play and initial introduction we were involved in a fight. Skipping the details, we won the fight but most of the party was severely injured and two of the other six were actually unconscious.

We were about to wrap up the session and get back to town, but I've stopped them because I was struck with a (not so) brilliant idea. Since my character was "chaotic evil" (like a really evil guy for those with no D&D background). I've decided that I will now try to take advantage of this opportune moment, and try to kill the remainder of the party for personal gain (since it was definitely something my character would do). After some initial confusion I started fighting the rest of my party and once again, skipping the details, I've won, but only because I've been incredibly lucky with the dice. At this point I noticed while some of my friends were shocked/surprised by the situation (but still having fun), the rest was clearly disgusted as what just happened meant creating new characters, starting new story etc.

Consequences

Now, I understand if my colleagues didn't want to play RPG with me anymore, because they didn't consider what I did fun, acceptable or they just plain didn't like it. However I never expected them to almost completely exclude me from their group, and that's exactly what they did.

The next couple of days the chat room we used in order to get together, meet for lunch, tea, coffee etc. was absolutely silent. No big deal, I thought that simply nobody was in the mood. The problem is that I've noticed that all of them are still doing those things together, just without me. This leads me to believe they created the exact copy of this chat room, with the exact same people participating, excluding me. What further convinced me of this is the fact that today not only did they go to lunch together, they also specifically (by name) asked everybody else in the room (since not everybody is using this chat) whether they want to come, excluding me.

The situation seems surreal to me as firstly it was not my intention to upset anyone, and secondly I find it really hard to believe that killing somebody's fictional character, can lead to such behavior, especially since they can rollback the entire campaign if they want to! My guess is that they are trying to "punish" me for doing what I did, however I find it childish.

My question is: What would be the best way to repair my work relations with my colleagues after such incident?