NewbieG 20

The campaign is nothing too difficult, especially if you change the settings so ammo and health pickups respawn quickly.

Ultimately it's pretty hard to get stuck because enemies do not respawn (or even heal) when you die and respawn. And since there's no penalty or real consequence for dying, you can whittle enemies and bosses down gradually over many lives. Even if you manage to get killed after only landing a few shots, you're still making progress.

If you want to see what you're up against, here's the first level: (Credit to Frukt Pirat Gaming)