It’s a tough game, no doubt. You have to know what’s coming to have a chance half the time, save often.
I just made it past the first boss without too much trouble having said that, primarily because I remember suffering my way to a solution years back. The main trick is to leave that invincibility floating in the middle of the large room next to the room with the red door. When you are ready to go through the red door, grab that and high tail it to the boss fight. Kill as many of the chain gun and homing missile bots as you can before it runs out (this should be nearly all of them), then grab the invisibility in the bottom of the pillar and kill any that are left.
Once it’s just you and the boss, it should be pretty simple. Essentially fly round and round the central column, if you see the boss in front of you shoot it but don’t stop still for long. If he fires a smart missile at you, keep flying round and try to hug the pillar and you should be safe.
The problem with all the above is that if you grabbed that invincibility the first time you saw it, you are fairly screwed. You also need to know the layout of the level before you go into the fight and where to grab that invisibility. There are bits like this throughout the game and it makes each level fairly gruelling. Even back in the day, I’d never want to play this for more than a couple of levels at a time. You definitely don’t want to grab an invisibility or invulnerability until you figure out why it’s been left there as there will almost inevitably be a room nearby that’s all but impossible without it.
There aren’t any bosses until the end after that first one. These first 7 levels were a kind of Doom style shareware version at the time which is why some of the bots and weapons don’t show up until after this.
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