It's frustrating that whoever plays last controls the narrative
It creates a disincentive for playing, and it makes narrative control a matter of timing rather than good writing or a good narrative fit. If you want control of a scene, the current system encourages you to wait and try to snipe control by playing only once the challenge is close to completion. But what if you have to be at work, or are asleep when someone else completes the challenge you were waiting on? Part of the idea of Storium, I thought, is that you can play whenever your timing works out for you (so long as you do manage to regularly play), but right now that just isn't true. If you're in competition with other players for any reason, then not going last is a very serious disadvantage, and those who can't afford to just sit around at their computer obsessively checking on the completion rate of a scene aren't going to come out on top most of the time (unless they get lucky).
I'm not sure what the best solution to this is, but I think there are a couple of factors to keep in mind. One is whether it makes sense for the person who played last to get control. For example, I'm playing in a game where several players were independently climbing a mountain, and I played first. Yet the person who played last got to dictate that she arrived at the top first, purely because she played last. To me it makes more narrative sense to say playing sooner helps you out more in a race than playing later.
Another factor is how many cards you played. If one person plays four cards, but the last person plays one, the last person still controls the narrative, despite having much less of an effect on it.
Finally, the appropriateness of the cards could also matter. Someone who had a "Mountain Climber" card might perhaps get more weight in deciding the outcome of a mountain climbing race, for example.
Anyway, these are just the thoughts off the top of my head. All I can really say for sure is that I find the current system for determining narrative control frustrating.
Thanks for your time.
These issues can be addressed through the narrator’s use of challenges – perhaps they could make smaller, individual challenges so that people are not in competition to play more cards/play last. The narrator may also want to consider how the outcomes are defined so that it does not contradict the flow of the narrative once the end results are met.