Thanks to the portfolio of a lead UI programmer who worked at Firesprite, one of many Sony-owned studios hit by layoffs in 2024, we know that the Twisted Metal game the studio was working on was
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"a 3rd person vehicular action combat game" that had "3rd person shooter mechanics wrapped with 3rd person vehicle combat with the objective of being the last one standing." (Thanks, MP1st.) Sure sounds like a battle royale game to me, though admittedly every Twisted Metal game sounds sort of like a battle royale, even though the series predates the trend.

Apparently the canceled Twisted Metal game would have been a battle royale where you could get out of your car for some reason
Twisted Metal battle royale does make sense.