Our terms of service prohibit the use of VPNs, proxies, or other methods that obfuscate your IP address. Our offerwalls' terms of service do the same.
This is because large parts of the offerwall industry are built on matching offers (and the advertiser paying for the offer) to the right people. If you use a VPN, you won't be matched to the right offers. If enough people did that, advertisers wouldn't buy offers, and the whole thing would collapse.
Offerwalls often issue chargebacks and reversals when they detect VPN use. They can also ban users from accessing their offerwall when they detect a VPN. We, too, might ban members when we detect VPNs.