I agree with you. You could have an entire game where every level is a total bore, ends quickly, etc. It's definitely more fun when you get higher gem cards, mixed well with traps. And a "traps only, level is over" can happen far too easily. If I own a game, I always play a fake game with myself before ever trying to teach anyone, and this kind of thing happened with regularity in my fake games (several), but there were rounds that went quite well and were fun. (I had a "strategy" for one of my fake players to be outlandishly gutsy, which got a bit funny.)
When I then pulled it out at my group, I warned them that sometimes it can fall flat like that, and you just start again and don't worry about it, and they accepted that. We didn't have many bad rounds but they were at least forewarned.
But I also got the weird feeling that no one thought much of the game anyway. We played it twice fairly quickly. One guy was just getting silly cause he would never leave - I think he got bored. I heard it was better with more people, but I thought it was worse with more people. That does create more tension in wondering who is going to leave (especially if there's an artifact up for grabs), but overall I liked my fake game with 3 people better.
I think one thing that made it more difficult with more people (which won't affect it here) is that it's difficult to see the cards, and difficult to tell the difference between them across a table and with tents everywhere, and seemed like a big waste of time a lot, like those situations when you know no one is going to leave. There are some other weird things about the game that you probably wouldn't notice playing here (like how remarkably stupid it is to
shuffle the artifact cards and hide them under the temple cards), so in the overall scheme of things, I just don't think much thought went into designing/testing this game.
I can think of a couple of people who weren't playing that night who might like it, and it comes in handy as a filler. But there are certainly better fillers.