Show us a pic of the backbox lit up. Let's see how bad the cracking is. You might be able to hide some of it with some colored LEDs, but the low light ones, so as not to have any hot spots.

The right way is how Chalkey mentioned.

Quick way...
1. Seal whole backglass with Triple-Thick.
2. Black Sharpie paint pens over blacks, if cracked. I put mine on an easel so I had light coming through to see where I needed black
3. Color LEDs, usually red behind Gorgar and blues/greens or yellows behind background.

Playfield looks pretty nice. I vote for new backglass. I bought my new one from Planetary Pinball but I see that they are out of stock. Picked it up at a Expo so I avoided shipping.

Hard to decide because the game just isn't worth that much so hard to justify a lot of expenses. It's the game we grew up on, and my dad's favorite, so it's a keeper for us. I've got way more into it than it's worth. New backglass, new boards and I redid the cabinet.

Try these first, if you want... might work and be easier to look at. Reds behind gorgar, yellows behind the people and blues and greens in the periphery.

https://www.pinballlife.com/index.php?p=product&id=1882

I threw some red legs from Pinball Life on mine after my cabinet restore. I bet the all black would look sweet though...

Gorgar (resized).jpg