Yep, I know, I know. I'll try to keep this one short. I'll happily admit, I can't really add much more about this game that hasn't already been said.
I remember my first few games when I got my Speccy in its early years - most obtained as Christmas presents and the like (being too young to work for my money at the time).
As a naive child, my game requests would be based on how cool the advert/inlay looked. So using this sort of criteria, the results were 3D Tunnel (meh), 4D Terror Daktil (not too bad I suppose) and Translyvanian Tower (visibly shudders). Jetpac would have been a game changer compared to those back then, but it wasn't long before I was able to play it.
Jetpac was released as a 16K game, and was available as one of the few early ZX Spectrum ROM cartridges - though good luck obtaining one now as they're pretty rare (no pun intended). There was also a Sinclair Research release of the game, which will also set you back a few bob if you decide to fork out for one on eBay.
I doubt I need to say much about the game - you fly around on your Jetpac, shooting aliens, collecting ship parts and then fuel that drops randomly from the top of the screen. And you can pick up the odd score-boosting alien item while you're at it. There are 4 different rocket ships for you to build, plenty of fuel to collect, and an assortment of different aliens.
The alien movement styles vary. Some fly across the screen, others move haphazardly, or zone in on your position. Some explode when they hit the scenery, others just bounce off.
For some alien waves it's safest to lurk at the top of the screen above the three platforms. Later on, homing enemies force you to think differently. The screen is wraparound, which adds an extra strategic dimension for collecting items and alien avoidance.
Your laser fire, rather than single shots, is satisfyingly expansive, as you fire multiple laser lines as you rise and fall. It also wraps around the screen, meaning you are continuously hitting enemies and increasing your score.
A few Jetpac-related snippets in recent years that you may or may not already be aware of:
Something that strikes me after going back to Jetpac after some time is that it's quite an easy game to master. After a few goes I found I could clock the game without too much trouble. But that's OK. There are a couple of enemies that home in on you so you have to take a bit more care on these levels, but nothing too taxing.
One criticism of the game is that the screen platforms/scenery don't vary in position at any point during the game. It doesn't detract too much from the game but a bit of variation might have added to the challenge. You could always check out the disassembly and POKE some different values yourself if you like.
Normally I'd say something about magazine scores here, but Jetpac is one of those early games that arrived before the main/popular magazines started putting scores in their game reviews and features, so not a great deal to say.
Nevertheless, it was highly rated by Computer & Video Games magazine (also winning Game of the Year and getting a Golden Joystick award), and was clearly recognised by the other magazines as a quality offering.
...So... Yep, that's about it. Definitely in my top 10, a game that truly stands the test of time. Ultimate Play the Game in 1983 were truly showing the 8-bit world how games should be done.