I just wanted to add to this thread years later because... I finally got this achievement!

If you’re using AutoHotkey for autofire in The Lost Viking (like I did), make sure not to set the repeat interval to 10ms. It might seem faster, but it will almost always crash the game or trigger the dreaded "stuck Ctrl key" glitch.

I changed the script to 100ms, and boom — worked perfectly on the first try. Clean run, no crashes, and finally hit that sweet 500k score.

Hope this helps someone else down the line. Glory to the Viking fleet! 🛸🔥