Prior to OSX and the integration of obj-c as a first-class citizen in GCC, Objective-C made very little sense. It still makes very little sense for a game, as

Prior to OSX and the integration of obj-c as a first-class citizen in GCC, Objective-C made very little sense. It still makes very little sense for a game, as C/C++ have a broader spectrum (in both tooling and target audience). Most of these game clones predate OSX/iOS (which popularized Obj-C) by a large margin.