That depends on what you mean by “real game dev”. I did a few game things of my own in BBC BASIC, eventually with a bit of 6502 assembly in key places, back in the day. On those machines you can still happily run a basic game loop in interpreted BASIC, the whole thing for text-based games, you just need to get down to the bare CPU for things like sprites, other rapid graphics drawing, and maybe some other number crunching (I did some basic compression in assembly for lots of text, though it wasn't really effective, if you are already doing graphics in assembly, then it probably makes sense to do collision detection and such there too, etc.).
C64 BASIC is kind of a mess, there's zero support for graphics and sound. Your code rapidly becomes a giant pile of POKEs and PEEKs, and all your operations become absurdly slow because all the math routines are floating point only, so there's a ton of integer/fp conversion overhead on something as simple as "peek a memory location, AND/OR it with a few values taken from variables stored as floating point, poke it back".
Assembly becomes really attractive really quickly.
C64 Basic did have integers.
A floating point
A$ string
A% int
as you would expect ints are quicker.
Err, ints are internally stored as floats as well and that leads to some really interesting performance quirks where you'd not expect.
There were BASIC compilers for C64 which generated significantly faster code just because they actually used ints for integer operations.
BBC BASIC was far better than C64 BASIC.
It had a nice set of built-in graphics functions and an inline assembler, amongst other things.
I can still remember that VDU 23 was the command to redefine a character, so much easier than doing the same sort of thing on the C64 (copy the character set from ROM to RAM, get the VIC to use the RAM copy with POKE statements, modify the desired character)
C64 Basic was V2 of a dialect of the Microsoft derived Basic for the PET. It was out of date already compared to the latest V4 because the older version fit into a smaller ROM to save costs.