I own CW3 on steam, but due to steam's restrictions on proxy servers (they do not allow their use at all), i cannot play at work. (im allowed, just we have an explicit proxy, so no way to get steam to work).
is there a way to get a non-steam copy to play?
You could uhmmm ... buy ... it? ;)
yes, i realise that. some games offer the versions however, as long as you have a verified purchase.
You can redeem a Steam key if you buy on knucklecracker.com, then you'll have both versions, but there is no reverse method.
Best you can do is write an email to support@knucklecracker.com with all the purchase details you can find and hope for the best.
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For those who might stumble upon this post looking for how to get a Steam key if you bought on the website, it's here: http://knucklecracker.com/creeperworld3/steamkeys.php
Are you sure that Steam disallows proxies entirely? I thought that their terms of service just prohibited using a proxy to spoof your location in order to access a region restricted game in a location where it is not available. I do know that there are some threads in various places on making Steam work through a proxy.
https://superuser.com/questions/387856/getting-steam-exe-to-run-through-a-http-proxy