Top image: Pavel Danilyuk – Pexels
You can call it a live compiling tool for Unity. Hot Reload lets coders skip Unity compile times for real-time updates while changing code. A feature Unreal devs are accustomed to, but has been a bottleneck for Unity development for years.
Hot Reload works pretty much as you’d expect Unity’s default ‘hot reload’ functionality to work, but with significantly faster compiling and no domain reload so variables stay intact. It’s a C# compiler which only compiles changed code. It works both inside and outside of play mode and supports almost all C# code changes. The benefits for most people come from iterating and making changes inside play mode though.
The developer created Hot Reload initially as an internal tool while working on their own project Mobile Minigames. When they conducted a productivity analysis a couple of years ago, they learned that iteration times were the single biggest bottleneck in the workflow. “Our project is currently more than 2 million lines of code, so we were looking at 2-3 minutes every time we made a change”, says CEO Reese Leysen. “At a certain point we felt forced to come up with a solution to reduce our iteration times. Even if we invested months of work, cutting out the iteration times would be worth the effort.”
So the team went to work. It took around 6 months to develop and test the in-house version so it was reliably working with their own game project. When it was clear that the tool actually saved the company time and money, rolling it out as a tool for other Unity developers seemed logical. “For the public release of Hot Reload for Unity, we spent around a month developing the tool”, says Leysen. “This included supporting new use-cases requested by users like editing generic methods, improving the editor extension UI, decoupling it from our game codebase, implementing licensing, and a bit more.”
The value that Hot Reload brings is often dependent on how long compile times are. So the pricing is fit accordingly. That means devs with Unity Personal can use Hot Reload for free, forever. Larger studios using Unity Plus/Pro/Enterprise can try Hot Reload with a 30-day free trial followed by a free 2-hours a day until the monthly/yearly subscription is purchased. “We believe this is a fair way of pricing Hot Reload”, adds Leysen. The value it brings to smaller studios is often smaller, while the impact on larger studios can be quite massive. We estimate that bigger studios can save thousands of dollars per year this way.”
Hot Reload already has over 1000 users, both free and paid licenses, and the response is positive. “Many people have even commented on how strange it is that Unity doesn’t already have this functionality built into the engine itself”, says Leysen. “And many people wonder why Unity doesn’t just buy the tool outright!”