Rather than think of Big Rigs as a "game" in the standard sense, I think of it more like what a game is built on that just has a few objects loaded into the world. Things like ground and terrain are loosely defined because that's what the game needs to know in order to build the world. Buildings have no collision definition and things like physics are unspecified because those things must actually be coded. So your truck is able to move through the world but without limitations (climb vertical slopes with no loss of velocity, leave the game world, and drive in reverse at an unlimited rate of acceleration). The truck is almost irrelevant, it's more just a camera that has an object that follows it as it moves through the environment (and game engines do have a defined camera so this adds credence to the notion this is more a raw engine than a game).
Calling it a "video game" assumes that it was built with the purpose of giving the player an experience that would somehow immerse them in the digital reality, no matter how tenuous (some may say that to be a "game" it must have a victory condition but things like Animal Crossing lack a defined objective other than living your character's life, so there is more to it than that). However Big Rigs in its infinitely unfinished glory, cannot make such a claim due to its inherently world-breaking incompleteness. So there is no immersion to be found, due to having no limits and unpolished content. No one could ever actually absorb themselves into the setting and, thus, I cannot actually consider this a "game". However if someone had the dedication, I'm sure they could take what is here and make a game of it...at some point...
This is more like a game engine than a game
Rather than think of Big Rigs as a "game" in the standard sense, I think of it more like what a game is built on that just has a few objects loaded into the world. Things like ground and terrain are loosely defined because that's what the game needs to know in order to build the world. Buildings have no collision definition and things like physics are unspecified because those things must actually be coded. So your truck is able to move through the world but without limitations (climb vertical slopes with no loss of velocity, leave the game world, and drive in reverse at an unlimited rate of acceleration). The truck is almost irrelevant, it's more just a camera that has an object that follows it as it moves through the environment (and game engines do have a defined camera so this adds credence to the notion this is more a raw engine than a game).
Calling it a "video game" assumes that it was built with the purpose of giving the player an experience that would somehow immerse them in the digital reality, no matter how tenuous (some may say that to be a "game" it must have a victory condition but things like Animal Crossing lack a defined objective other than living your character's life, so there is more to it than that). However Big Rigs in its infinitely unfinished glory, cannot make such a claim due to its inherently world-breaking incompleteness. So there is no immersion to be found, due to having no limits and unpolished content. No one could ever actually absorb themselves into the setting and, thus, I cannot actually consider this a "game". However if someone had the dedication, I'm sure they could take what is here and make a game of it...at some point...