To follow up this reddit comment might be a good place to start. There is also some documentation on hackaday
So, to be clear, I would not be able to put a game on an actual Nokia 3310. I'm not big on handling hardware, and I mainly follow such restrictions as a design challenge. If I come up with an interesting idea for the jam, it's going to be made using my goto game dev setup (SDL2 + lua 5.4).
That said, it does appear that the dev tools hackers used back at the height of the 3310's usage to develop games are still right there in the NokiaFree archives and on sourceforge. The main thing missing is the flasher utility that was expected to be used.
Back to the main topic, I found a site with repair information here . It lists the speed of the processor as 13 MHz, but with further clarification using hardware jargon I'm not familiar with. The next two pages for reading then clarify how the phone's flash card was used. As the hackaday link showed, the flash card is 4 MB (and I found multiple links to legally questionable ROM uploads helpfully listing the size without the need to download them) but only the second 2nd half being relevant for programs. My guess is the first quarter or so is a combination of drivers and BIOS stuff. For example, a post on NokiaFree's archives mentioned some bytes to poke in that range to overclock the processor, but with no one seemingly knowing the side-effects. The repair site also separately mentions "scarap" memory, which I'm guessing is code to go along side "beetle" memory (with scarap being a typo for scarab) for the program data. Scarap memory is 1 MB, so I'm guessing that's basically additional memory to be used like RAM, if possibly slower since it's still flash memory. Beyond that, the processor chip itself also has 1 kB of memory. Also the repair site mentions 128 kB of "work memory" that it clarifies as "data", unhelpfully.
Going by the hackaday link, it would seem the expected sections of the 2 MB are 1280 kB for the firmware (no idea if it actually uses all of it, since I don't have what's needed to run the dev tools and see), 576 kB for the creative assets, and 192 kB for the program data.
So, as a rough estimate, using a RAM, speed and size of 1MB, 13 MHz and some loose judgement of 1.5 MB beyond engine size.
Nice research. I never owned a 3110, always felt those phones were expensive and difficult to use (compared to Motorolas and Alcatels, which ironically my nokia-owning friends found difficult).
My dad had one and I think he still has it, with a dead battery.
Having REAL memory limits would mean having to use old-school techniques, such as real 8-bit monochrome graphics.