I've been playing through the main campaign with my friends, and it's been a slog. Most of the missions we get overwhelmed quickly. The alert level seems like it escalates too fast sometimes. The last mission we played was mission 7, which was insane. The Charontid's plasma weapon dropped two characters in one activation. I feel like maybe we're playing the game wrong? Are there rules I'm misunderstanding? Is this game just hard?
I haven't made it to Mission 7 yet but yes, my group is finding the game hard. We haven't found any mission insurmountable but we've been pretty close to getting wiped out on several of them. We're still having a blast though as it forces us to carefully think through every challenge, which is a nice change from some games where you end up roflstomping the enemies after a certain point.
Unidrons are not your friends. Having 12 shots a turn, 6 of which were unopposed against 75% of the team, was pretty brutal for Mission 1.
Game is very punishing, the first mission is brutal especially and it tends to snowball if you fall behind. One little house rule we tried to ease the pace a bit was to reshuffle the AI Card back into the deck if you wipe out the Enemy Unit before it activates. It kept us from getting snowballed into Max Alert within a few turns but doesn't actually stop it happening.