A ripoff or copy isn't the same as a tribute. Dead Souls admittedly just copies-and-pastes its various enemy ideas from other places, but none of it ever comes off as some kind of gracious homage to whatever came before. They're just copied ideas, following the popular zombie trend. It also features screaming zombies who attract more hoards to attack, and giant hulking ones that ram you. The ideas are just like Left 4 Dead (or whatever used the ideas before), but it's never presented in a "kudos to you!" nod to those previous efforts.
And Undead Nightmare is nothing like House of the Dead, so if it was intended as a "tribute," then they did an inadvertantly good job at sidestepping any indication of their inspiration (besides the basic subject of zombies).