I've lost count how many times I've been asked the question, "Tip, how do you open a
Neo Geo home cartrdige?" Well, here's my answer... pretty low tech but it works for me.

You have to be really careful. I generally start from the front of the cart.
Once you pop the two front "tab" connector points then work around to the sides
of the cart and gently push the plastic tabs inward. You'll get what I mean
once you've seen the carts insides. In most cases I can pop'em now without
even causing damage to the label. On one occasion I broke one of the tabs.
I generally do not use any tools as they can scratch or otherwise deface the
cart. I hope this has been at least a little helpful to you.