My bad, there is actually no option for toggling mouse-aiming on or off, so it should be always be active.

Some quick troubleshooting that I can think of:

1) Reboot your PC
2) Reinstall the game
3) Unplug any gamepads (if you have any)
4) Use a different mouse (if you have any)
5) If all the above fail, download the latest version of eDuke 32 and run the game through there (make sure to put Ion Maiden.grp into eDuke32's directory).
http://dukeworld.duke4.net/eduke32/synthesis/latest/?s=d&o=d&dir=eduke32/synthesis/latest

I'll admit I never thought of these. As I said the mouse works in Ion Maiden's menus, but as soon as I start the campaign it just doesn't respond to any input. If I pause Ion Maiden, and bring up the menu, there it is again working perfectly. So I don't think this could have anything with the mouse device.

However, I did start playing Dangerous Dave recently and I do have a controller plugged at all times for it, so I guess I'll try your advice when I get home.

Well finally!! Bombshell was pretty much the definition of boring and disappointing. Good to see that me buying the Deluxe edition in hopes that it was worth paying the extra 2 or so dollars was good for at least something and I will download the preview campaign once I get home. Bombshell was a failed experiment and luckily, they realized it and went back to FPS. It being on Build is just a nice bonus.

Just grabbed this on Steam and played the first level. I thought it was EXCELLENT and well worth being excited about. Mouse aim does feel a little off but they say they're working on that. Otherwise it was about everything one could hope for, IMO. I hope the rest of development goes smoothly so I can play the real thing in 6 months like they say.

Just to let you all know the Preview that is included with Bombshell Deluxe has been updated, full change log:

Important Notes:

User data is now stored in "%USERPROFILE%\AppData\Roaming\Ion Maiden Preview Campaign" on Windows and "~/.config/maiden" on Linux.
The save format version number has been bumped, meaning your old saves will no longer work. This may happen repeatedly during the Early Access period.

Changelog:

1) Overall Performance Boosts!
2) An occasional crash when performing random actions, including flipping lightswitches, has been fixed.
3) A bug that would cause the player to sometimes switch to the wrong game mode when loading a game has been fixed.
4) Optimizations to the game world logic have been made to improve performance in some circumstances and shrink savegame file sizes.
5) Mouse aiming has been reworked to allow much greater precision of movement.
6) The mouse axis scale sliders can now go all the way to zero.
7) New "save setup" menu, allowing autosaves to be disabled and a limit to be set on the maximum number of autosaves to keep at any one time.
8) Savegames can now be deleted with the Delete key.
9) Keyboard bindings for aiming up, down, and returning the view to the center can now be configured.
10) A key or button can now be assigned to switch to the player's previously selected weapon.
11) The sizes and brightness of certain pickup items have been increased
12) Armor fragments are now more visible.
13) Awkward delay after SMG reload has been fixed.
14) The easiest skill level should now be easier, and the hardest should now be harder
15) Volume slider no longer treats 50% as 0%

Sorry for necroing this thread, but there's been an update and I thought I'd use this thread for a shoutout (for all those that didn't get an update flag like me).

Changelog:
Heskel's House of Horrors Update (28 January 2019)

This new update includes tons of new features and additions. One of these is a new Secondary Firemode! If it's not already bound, PLEASE bind your Right Mouse Button to "Alt Weapon Mode".


Gotta say, the new level is amazing. :)