It's mine too, I PM'd xshadowstormx about it and got this: New resolutions should be added before we are final. Thanks for your time in sending feedback. -Logan so should come sooner or later.
In the meantime you can very easily open \Documents\My Games\UnrealEngine3\HostileGame\Config\HostileEngine.ini and edit ResX and ResY (line 730) to your desired resolution.
This is one of the areas we are going to tweak. The way it works now you can try picking the closest resolution to you native and it should "snap" to it. You can also just change the .ini file as mentioned above to any custom resolution you want.