After purchasing the game here and noticing the ads for an arena mode, I found the free to play arena mode on steam with a premium version that imports content back into Legion Rising. Is there a way to get these weapons and modes on GOG?

Edit: All the reviews refer to it as a demo, I might have misinterpreted it and it's already been included

FINAL EDIT: Question answered by developer in game, Arena is free and GOG doesnt allow free games. WIll hopefully be patched in soon.

I'd just like to be able to get the magnum you can get from getting the Arena supporter pack.

Even if the dev can't get arena onto GoG I hope he can add another dlc that covers the supporter pack.

I'm a really big fan of the game and I'm happy to pay for the dlc to get the weapons but I'm not happy to harrass my friends into playing stuff.

I'm not sure if I can get the arena support pack on steam and get it to work on this account.

Can anyone confirm?

That seems.... odd, to say the least. There have been quite a few free games on GOG for a long time now. To name just a few:
Jill of the Jungle
Lure of the Temptress
Beneath a Steel Sky
Classic postal