As I've probably observed in the past, there's one aspect of the films that we haven't yet figured out how to capture in a game mechanical way. Namely, Indy doesn't actually defeat the enemy. He finds the artifact, but then the enemy swoops in and take it from him almost immediately. But then, the enemy operatives are undone by their own hubris.
Steve has suggested, and I agree, that the game might be more interesting if the Nazis aren't NPCs, but instead are represented by at least one player. And a playtester suggested going all the way in this direction, to where all of the players are Nazis, and are all following Indy (an NPC), jockeying to position themselves to pounce right at the right moment. I think either of these would work but I do suspect that some players would be uncomfortable being forced to play the role of the Nazis or even "the Enemy". It would reduce the audience for the game somewhat.
So, the compromise solution, in my mind, is that each player gets 4 starting Equipment cards. All players have the four canonical "Indy" items -- whip, pistol, fedora, satchel -- on one side of the cards. On the back side of the cards are equipment items that correspond to a character who is perhaps a bit more "grey", shall we say, with respect to ethics and motivation.
I realized that this might give an opportunity to introduce the idea of hubris after all. It could function something like corruption in Cleopatra and the Society of Architects. It's a currency that you receive in exchange for taking more powerful actions, but it has a bad effect at the end of the game. And if these effects are tied to equipment, it should be basically seamless; i.e., it doesn't need a separate set of rules to police it.
As for the bad thing that happens to you: I think we need something more interesting than the obvious "whoever has the most hubris at game's end automatically loses". This game is about risk management, and so it would be most appropriate for hubris to expose you to risk. My first thought is that maybe it's as simple as: if you are first to exit the temple with the artifact, you must face a "hubris" challenge. I guess you would have to roll dice in the same way that challenges are typically resolved, with white dice giving you check marks and red dice giving x's. You must roll as many check marks as the number of hubris tokens you've acquired (i.e. each success lets you "discard" a hubris) before you roll some number of X's, which is maybe scenario-specific. So, the more hubris you've taken on to improve your position or hurt your opponents' position, it will make that final challenge harder to pass. And if you fail, the next person takes their chance, and so on. Of course, if you fail to recover the artifact successfully in the first place (e.g. you choose poorly for the grail), you don't even get to this point.
I suspect this will be tricky to balance but in principle it seems doable.