The RAGE engine used in GTA IV links its physics calculations directly to the frame rate. If the game runs above 60 frames per second, you will experience broken physics, erratic camera shaking, and an infamous bug during the final mission ("Out of Commission") where Niko cannot climb into the helicopter.
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Grand Theft Auto IV (GTA 4) on PC has a tumultuous history. While lauded for its storytelling and physics, the original PC release was infamous for poor optimization and technical issues. Over the years, Rockstar Games released several patches to address these, with widely recognized as the pinnacle of stability and compatibility, particularly in the modding community. gta 4 patch 1070razor1911zition