1) It must be obvious but not trivial

In any hackathon, you will have at most a few minutes to present your idea, and it will be judged by a panel, not by the market. Not your target customers.
The goal is to provoke a reaction like: “WOW, why didn’t anyone think of this before?”
To achieve this, your idea must be immediately recognizable as the solution to the problem you identified. You don’t have hours to convince them it’s the right solution, but at the same time, it shouldn’t be trivial — because judges forget trivial ideas first, and if it’s trivial there will likely be similar ideas, increasing competition.
Here we already notice the first difference with a real startup: a less obvious idea is not necessarily doomed to fail.
For the market, the WOW effect is important, but it’s not the main reason. Customers care about whether you solve their problem, not how strange or counterintuitive the solution is.
A clear example is Airbnb: “Rent my house to strangers? Meh.”
Crazy idea at first glance, and yet now Airbnb is worth around 80 billion.

2) It shouldn’t be too niche

Again, the presence of a jury plays an important role, and they probably don’t know all the problems in the world, only the more general or familiar ones.
Therefore, it doesn’t make sense to create an idea that solves a very niche problem, because you won’t have time to explain why this problem is so urgent.
It’s better to stick to more general and easily understandable problems.
When building a startup, we want the exact opposite: a small number of people willing to pay a lot, not a large number of people moderately interested.
Also, we interact directly with our target customers, who already know their problem well and are actively looking for a solution.

3) The prototype must be easily achievable

In the previous two points, we basically said that the more “sci-fi” an idea is, the easier it will be to win — and this is true — but only if you can actually make it, or rather, only if you have demonstrated that you can make it. This is the secret.
Here the prototype comes into play, capable of saying: “I’m not just dreaming, I can really do it!”
The prototype doesn’t have to be a finished product, just something that shows it’s possible to reach the complete product. It doesn’t need all the features, only the essential ones (e.g., a solar panel that works with algae → a small-scale test to show you can extract an electrical signal from a leaf).
The difference with a startup is subtle and lies in the different purpose of prototypes versus MVPs.

• A prototype is primarily about testing feasibility — whether an idea can actually be built, if the technology works, the design holds up, or the mechanics function.

• Instead, the MVP is about testing what could actually work, which features people want, if it solves their problem, and if they would buy it.

4) Economic unsustainability

In a hackathon, you are only asked for an idea, not to turn it into a real product or immediately bring it to market. So, it’s not necessary to obsess over the right price, whether revenue will exceed costs, or after how many years you will break even. You simply can’t deduce these things from the idea alone.
It’s still useful to start thinking about its economic sustainability, but only in a general way and just as a protection against potential questions from judges (you can expect at least one question about costs and revenues), without going too much into detail.
In a real startup, however, this point becomes crucial, because whatever you create, you will need to pay your employees, suppliers, and investors — and to do that, you need to generate profit.