Verify your cache: https://support.steampowered.com/kb_article.php?ref=2037-QEUH-3335

If you're running Windows, disable your antivirus software or white list the game files: http://wiki.gearcity.info/doku.php?id=troubleshooting:antivirus

Try running the game from the GearCity.exe instead of Steam.

If it still fails, email me the log files: http://wiki.gearcity.info/doku.php?id=troubleshooting:steam_logfile

If you're not running Windows, launch the game from a terminal. Let me know the output.

(Side note, your profile here on Steam says you're in game. So you might want to reboot if you aren't in-game.)

Problem solved. All good now.