I owned this game back in the dos days and I remember that you could start on training and once you finished the training levels you started on the next difficulty (rookie) with your money reset but you retained all your weapons you bought.

It even says it in the manual - however, it completely resets everything back to square one.

This is, as others have said, not a very good port.

Ah well, only paid $1.50 for this on sale.. guess I can't complain too much....

Funny - I owned the original game (shareware + paid for full) and it did. Also, it states right in the manual (on gog.com) - which appears to be the original manual - that you will be placed back at wave one with no money, but you will retain all the weapons acquired from the training.

I haven't played any farther past completing the training mode - I hope that doesn't also do that to the other difficulty levels; kinda defeats the purpose of building you ship up... Maybe someone can confirm that it works as intended on those levels?

Again, not that big a deal really - I bought it on sale for a $1.50; and it is still quite fun to play.

Could be because of different versions of the game. Since updates were almost impossible to do back then, if the company released a couple different versions people most likely wouldn't know & most likely wouldn't be able to update. Could be the one GOG uses had a bug vs a different version.