Every feature that amber has, the good features from Purus, and some things from Ender. Same rules apply as with those other clients, Java version 8 64 BIT, etc. Support is best acquired via Discord's "bug-report" channel. If you post a bug-report that is literally just "lol i crashed" with no further details, I'll probably ban you and not feel bad about it in the slightest. This is a free client that I'm under no obligation to you to support or upkeep, so if you want support I'd recommend not being annoying. Have fun. I use about every bot that is in this client, so if it doesn't work for you - it's probably you. The discord has instructions for how to use almost all of them, so don't ask me how if it's in that channel.
Java
In my experience, on most computers, everything seems to run with fewer issues using the 64 bit version of Java 8.
Downloader - The updater should start the game when it's done, potential reasons it wouldn't include wrong program association with jar files and improper folder permissions. Ensure that the folder this is placed in has read/write permissions.
Client is discontinued. Use Amber instead.
If you have issues using the updater, you can download standalone rar versions as well but will need to monitor discord for updates and re-download.
Client is discontinued. Use Amber instead.
Source
Client is discontinued. Use Amber instead.
Discord
Client is discontinued. Use Amber instead.
Key Features
Honestly, there's probably too many to list. So here's a link to the changelog instead.
Client is discontinued. Use Amber instead.
Client based on:
Amber
http://www.havenandhearth.com/forum/viewtopic.php?t=40400
Purus
http://www.havenandhearth.com/forum/viewtopic.php?f=49&t=43840
Ender
http://www.havenandhearth.com/forum/viewtopic.php?f=49&t=40754