Unfortunately, I think the second level might be where it gets hard. In fact, this might be as far as I got when I tried Heroic mode once. I forgot about that until now. I didn't try very hard though, because the thought of not having checkpoints was demoralizing. I probably won't even finish this run through Insane mode before I get pissed off enough to uninstall.
What I remember most about this game is that it looks cool but it's just frustrating to play because you move like a tank but don't take hits like one. The "sprint forward for 1 second" button feels like an insult.