Example SConscript

SConscript

# returns the directory
def build_app(env, target, source):
    env.Command(target[0], source[0],
        [
            Mkdir("$TARGET"),
            ...
        ])
    return [target[0]]

build_app_bld = Builder(action = build_app,
                        suffix = '.app')

game.Append(BUILDERS = {'App': build_app})

source = Split("...")

game_obj = game.Object(source)
prod = game.Program(target = 'game', source = game_obj)

app = game.App(target = 'game.app/', source = prod)

# Doesn't work (has error shown in question)
game.Zip('game.zip', 'game.app/')

# Also doesn't work (does the same thing as above)
game.Zip('game.zip', app)

# Other things that haven't worked
game.Zip('#game.zip', '#game.app/')
game.Zip('#game.zip', app)

SConstruct

SConscript('src/SConscript', variant_dir = 'build/')