The one you mention first that's connected to both the game board and a PC is the real emulator. Since it plugs into the board, it can also be used to troubleshoot hardware. The software-only one you mention second is a simulator, not an emulator. When you saw someone using simulator software, was it for simulating a 6502? The simulators I've seen are for particular microcontrollers or microprocessors, but are not able to simulate all the hardware I/O on a board with other ICs on it.
It is possible to set up your development system to have good development speed without any of these tools. Emulators especially are normally many thousands of dollars. Simulators, just being software, are sometimes free. I used Microchip's simulator a few times when I was new at using their PIC microcontrollers, but don't anymore because it's virtually worthless-- too cryptic, progress is too slow, etc.. It was marginally useful only when I didn't really know the instruction set yet.
Especially if you use Forth on the 6502, you can get instant turnaround between writing a piece of code on the PC and trying it on your board-- without taking time to re-assemble or transfer the whole image again over RS-232 or whatever. I realize however that getting that going too when you're not very experienced at the 6502 or Forth either is a bit unrealistic.
You'll probably do best to start small and write little building-block routines. Use those as components for bigger building blocks. These first two levels will definitely include some debugging routines which can be called at various points in your code where there seems to be trouble. They might be used to merely tell you that you got to a certain point in the program, or snoop around in your variables, edit various addresses before continuing on, etc.. It is a common pitfall for beginners to lack modularity and debugging utilities in their programming. Then they want to substitute expensive development tools for a clear understanding of the development process. I'm not saying the expensive tools don't have their place; but they're a very poor investment for most of us.
One less-expensive tool that can save time in some situations is an EPROM emulator. I also have an HP1610 logic analyzer here free, with manuals, for anyone who wants it. Someone gave it to me but I've never used it. He said there's nothing wrong with it but that it was taken out of service at work for the same reason functioning IBM PC-XT's were. If you're not close enough to come pick it up, it will probably cost about $50 to ship in the US.
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