1) Christmas credits. When you killed enemies over christmas rather than piles of shiny coins, mountains of wrapped packages appeared. It was just a graphical change but a fun one.
2) Christmas gifts. I think the 12 hour rarity boost potion was to do with the patch rather than christmas. A Hulk costume with Hulk in Santa hat was given for free, not any use to people without Hulk but a nice gesture. The cool christmas gifts were the ones you logged in everyday for. This was a bit bugged in that you had to log in twice for them to appear in your inventory. Apart from that everyday you got 5 cube shards, 3 odin marks and 10 eternity splinters. As this went on for about 10 days this added up to a fair few. It’s all in game currency and it was a nice boost towards getting new things.
3) Speed of patches. The game has been out six months and it’s all but unrecognizable from launch. They have done an incredible amount of work to turn it round in a short space of time. It inspires faith in the dev team, that if something is wrong then they will fix it. I ran into a bugged legendary quest, googled on the forums, a purple had already commented that they’d fixed it internally and it would be applied on live as soon as possible. They have bugs and make mistakes, they acknowledge when it’s gone wrong, work hard to fix it and communicate while they are doing so.
4) Community communication. The purples, as they are in MH, are very active on the forums. They regularly write posts explaining what they are currently doing, what they are planning on doing, what they know isn’t working etc. They give estimated dates for patches and comment on their progress throughout. This is nice as we know the direction of the game, we have things to look forward to. They also actively ask for community input, they don’t always follow it but I get the feeling they listen.
5) The test center. This is obviously where they get people to test their patches, so that bugs are found and they don’t break the live servers. However, I’ve seen more than once one player advising another, to download the test center to ‘try before they buy’. As you can access heroes for free on the TC. I thought this would get stomped on but I saw one purple encouraging it. I suppose if people aren’t going to pay money unless they like it, trying it and liking it will part them from their money. I thought that was nice.