Tube trap is very similar to Shopper, maybe more than Ropes n' Crates, not sure. Not sure if it can be considered a Shopper variation, because it has Sudden Death, rules are a bit different and the scheme settings are a bit different. The same question can be done to Rope on Ice,
Sally Shopper and other Shopper variations available on
Scheme ideas page. I focused on the variations available on Shopper article which are more known and "officially" recognised.