If we take a look at the most influential games ever made, they're nothing that can't be accomplished on any procedural language:

Tetris, Sim City, Pong, Gauntlet, Frogger, to name just a few.

In todays game industry the software is more, well-filled around the edges, and graphics play a major part in dragging in casual gamers drooling over eye candy

Saying that, speed differences between C++ and Delphi in many cases are minimal (or so benchmarks have proven), all it means is that games made using Delphi have to be extra lean and mean to keep up with C++ where it may fall short, and in theory that can't be a bad thing