How do you play the classic game Heretic natively on an Intel Mac?

If it’s PPC only, I would imagine it won’t run on your Intel machine. I’ve certainly never heard of PPC emulation to support PPC-only games, for example. I think your best bet would be to write to the game developer, but first try this:

Open the location you installed the game to. This is probably the ‘Applications’ folder at the root of your mac hard drive.

Select the game in the finder, and select ‘File’ > ‘Get Info’ on the menu bar.

On the info window, tick ‘Run using Rosetta’.

Close the window and try launching the app. With any luck it will run. If not why not voice that there’s at least yourself who would benefit from a truly universal binary to the game.

Thanks benseven; in case it wasn’t clear, I am interested in running the game natively,
that is, without a layer of emulation. I am looking for games that will not drain
the battery of a Macbook Air too quickly, not to mention the heat.
But because of the PPC -> Intel transition,
the usual trick of going back in time does not work for many games.

“PPC-only” in my question means that only a PowerPC binary is provided for the engine
in the Doomsday package that I found. It does run in Rosetta, only it uses as
much resources as a more recent game.

I may have used the wrong package, however, as I just found that this one
http://sourceforge.net/project/downloading.php?group_id=74815&use_mirror=dfn&filename=deng-1.9.0-beta5.1-universal2.dmg&4839178
does provide universal binaries for the engine and not just the launcher.
The “wrong” one is still floating around, and as I said initially, it looks
universal but it isn’t.

The universal version of Doomsday Engine runs smoothly enough with the default settings
on a 1st gen Macbook Air capped at 800MHz. I will take a look at the settings,
but for someone who is only interested in Doom, PrBoom (currently 2.5.0) is the simplest
choice.