(Mac Users) No Steam Login checkbox [WORKAROUND]
For those using a Mac and unable to login directly with the Steam account if there is no checkbox I've managed to find the solution to the problem. It turns out the newest version of Java, SE 6, for Mac is unable to recognize the Steam Login checkbox for Spiral Knights. Here's a few screenshots showing when I changed them.
Running Java SE 6: http://i316.photobucket.com/albums/mm349/borntobuild6/Picture2-1.png
Running J2SE 5.0 (64-bit): http://i316.photobucket.com/albums/mm349/borntobuild6/Picture1-1.png
To fix this problem just do the following
- Go to Spotlight (Top right of the desktop with the magnifying glass)
- Type in Java Preferences
- Drag J2SE 5.0 (64-bit) to the top
- Close window and start up Spiral Knights via Steam
One small problem is that other websites/programs running on the latest Java might not work with the J2SE 5.0, but it's very easy to fix. After you've switched it and logged in you can switch it back to Java SE 6 and continue on. If there are any problems let me know and I'll try assisting as much as I can.

You'd have to get it through the Apple developer site, which you'd need an account.
http://java.about.com/od/gettingstarted/a/javamacosx.htm
http://developer.apple.com/Java/download/
For those that are running Snow Leopard (OSX 10.6+) and don't see J2SE 5.0 in your Java Preferences, here are instructions on how to install J2SE 5.0.
Disclaimer:
Before following the instructions below, make sure you backup your entire computer. I am not held accountable for any damages done.
1) Download and Install Pacifist (http://www.charlessoft.com/Pacifist.dmg).
2) Get Java Update 10 for OSX 10.5 (http://support.apple.com/downloads/DL1359/en_US/JavaForMacOSX10.5Update1...).
3) Use Finder to go to System > Library > Frameworks > JavaVM.framework > Versions and delete the two aliases (symlinks) “1.5” and “1.5.0”.
4) Use Pacifist to open the JavaForMacOSX10.5Update10.pkg file that you downloaded (it's inside the dmg file you downloaded in step 2).
5) In Pacifist, drill down into Contents > System > Library > Frameworks > JavaVM.framework > Versions.
6) In Pacifist, select 1.5 and 1.5.0, right-click, and chose Install to Default Location. Use Administrator Privileges.
7) Now, you will need to edit 1.5.0/Resources/Info.plist in order to allow your system to allow the older Java version to run. In a Terminal window:
cd /System/Library/Frameworks/JavaVM.framework/Versions
sudo nano -w 1.5.0/Resources/Info.plist
8) Find the key JVMMaximumFrameworkVersion (use Ctrl-w to find) and update the value to 13.*.*
9) Go to the next key VMMaximumSystemVersion and update the value to 10.6.*
10) Ctrl-x to save the file and exit
11) Use Java Preferences app to verify that you have J2SE 5.0 installed.
Also, this should work in Leopard (10.5). However, I haven't tested it.
Thank you so much for the informative walkthrough, worked like a charm, only problem I was having was that I kept searching for "JVMaximum" instead of "JVMMaximum".
So after moving the J2SE 5.0 (64-bit) to the top, the Steam checkbox at the login screen still will not show up...
Any ideas why?

Check the projectx.log file again and see if it says "Steam initialized" in the 2nd line.
Also, did you restart the Steam client after it didn't work the first time?
I have Java SE 6 (64 bit) then (32 bit) and no others and do not have the issue that you are talking about. My steam has a checkbox and logs in fine (I have a converted account from prior to steam, not sure if that matters). 2009 iMac with nVidia and snow leopard.
Edit: Actually it occurs to me that I am launching the game via steam, which means it is probably using steams self-contained version of java. When I launch the game via the downloaded version it does not give me the option to login via steam. Is it possible that I would be getting better performance out of Java SE 6? Because I can't group at all right now for Vanaduke or JK thanks to performance based latency.

Alright, I've switched the default version of Java to "Java SE 6 (64-bit)", Now I can actually launch SK successfully, but there's no checkbox for steam login. I've already tried restarting steam. I've even tried switching the default version of java to "J2SE 5.0 (64-bit)" but that wouldn't even launch SK.
I looked at the projectx.log, and I don't see any "Steam initialized" on the second line.
Edit: This is what the second line of my projectx.log says: Loading: net.java.games.input.OSXEnvironmentPlugin
Anything else I should try? (I'm using OSX 10.5.8, btw)
I dont use steam as my os is not compatible.
i have mac os 10.4
the 5.0 is alreadt the defalt java...idk if it's 64 bit or what.
still doesnt launch the game. If they could fix ppl getting stuck in elevators an hour after the last update why cant they fix us getting locked out now? Do they not care about there mac ppl? i will unhappily go back to my wii games if they dont fix this.... and i want my dang money back too.
=[ hope someone in admin is out there reading this stuff

Way to bring a dead post back to unlife........ So it looks like we have a catch 22 for Mac/Steam users again. At this point Mac users are going to have to wait until they push out another update with correctly compiled files.
Sorry folks. :\
when exactly is that next update anyone know?
totally not cool....

It may go out as a hotfix, so it'll depend on how long it takes them sort out what happened, make the corrections, then prep the new build to get pushed out. Might go out as early as tonight.... but I can't say with any certainty.
mine just stopped working for me for some reason......... I HATE THIS!
I'm not able to log in as well. This sucks. using os 10.5.8

i think it's only affecting people with that particular OS
She played earlier today though. I think it has something to do with this recent patch, anyone know what's up?

Well it is clear that this issue seems to only be affecting mac users. I also think it's only effecting users with OS 10.5.#.
I don't know any way around the problem, so I'm pretty sure we will have to wait for a patch to fix the issue. I was on earlier in the day as well. It was only post-patch that I saw this problem. Found it very unusual as I've never witnessed it before.
Seems we will have to wait it out.

Add me to the list of people using 10.5.# who have met this problem. I agree that it seems likely to be specific to that OS, but haven't actually contacted anyone running the game on a newer OS.

I use Steam.
I use OS 10.5.8
Since the last mini-patch I can't login.
In the login window I only have "Login as Guest".
I logged in right before the update/patch around 5 minutes before and right after the patch was done that happened.............
SUCKS FOR ME!!! I CANT USE MY 100 MIST!!! :(

I've already sent a technical issue complaint to Spiral Knights Support.
Please don't bomb them with this issue.
I'm sure they're at work on it.
I hope we all can play soon and enjoy spiral knights again!!!! though i think all the people with this issue should get something for free but that would be too hard to do because some people would lie about it just for the free things.... :(

what did you do? i opened SK via steam, downloaded the patch, and it changed absolutely nothing for me... -_-
thought the patch was a complete fail, but if it worked for someone that's a good sign i suppose. Makes no sense...

Hey, okay everyone. If the patch is not working for you, check your java preferences. If you tinkered around with them before in hopes to get the game working, you may still have the same problem like I did.
Make sure you have J2SE 5.0 64-bit on the top. With Java 6 the patch will have had no effect.
Hope this helps if anyone is still having problems!

Thank you, Crabado. That actually worked. And of course, thank you Three Rings for fixing this only several days after the problem arose.
Hey,
I don't have J2SE 5.0 on my mac. I'm not really sure why, because I had a previous version of Java installed beforehand anyway. I heard I can get an older version by doing a system update... But I clicked system update, and it didn't suggest the older version. (which makes sense to me.)
Anyways, I'd be delighted if you know where I could download Java J2SE 5.0.