Personally I think this is just temporary. I have prepaid this game as well since the first day and I have nothing locked on my card at all.

Maybe you should call Stardock customer service I am sure they could clarify this for you.

they will hold it from you, but it shouldn't actually be deducted from your account.  It has something with the way credit cards are done.  When the inquiry to see if the card can be charged, the bank automatically puts the money on reserve expecting for charges to come through (food placed do that all the time, the actual charge usually being higher to include tip)  It shouldn't be held from you more than a week or so, and likely you can talk to a bank person to get it un-held.

What impulse does with pre-orders is that they post a test transaction to your credit card. It will appear in your pending transactions, and take away from your limit, but will not actually post to your account.

However, this pending transaction will clear after a while, depending on the speed your bank works at.

If you're using a debit card, I'm not sure how that's handled because I always pre-order with a CC.

Please contact sales@stardock.com as they may be able to help as well.