What should I build during a 40-day break to gain real software development experience?

A text adventure or small role-playing game is a good way to practice OOP without getting buried in infrastructure. Model rooms, items, characters, commands, and game state, then add save/load support and tests. The important part is to refactor as the project grows instead of treating it like a one-off assignment.

A local file-sync tool could be a useful project if you keep the scope under control. It would expose you to file I/O, persistence, configuration, state management, conflict handling, and possibly concurrency. You don't need to build a full cloud service—start with syncing two folders, then add logging, a dry-run mode, and better error recovery if time allows.

Start with a small project that solves a problem you actually care about. Write down the features, then deliberately cut the list down until the project can realistically be completed in a couple of weeks. A finished, tested application will teach you more than an ambitious codebase that remains half-built. Use version control, write a short plan and user stories, handle errors, and improve the design after the first working version.

Build something you would genuinely use, such as a simple login-based web app, personal tracker, or tool for an annoyance in your daily routine. Real motivation makes you care about usability and reliability, and you'll encounter things courses often skip: input validation, file or database storage, deployment, documentation, and confusing bugs. Several small projects can work well too, but give each one a clear feature list and finish it before moving on.

Don't rely on blindly copying solutions or asking tools to rewrite your code. Use documentation and automated assistants to explain errors or suggest areas to inspect, then make the changes yourself. Deploying a small project to a server and writing tests and documentation for it will provide more practical experience than simply completing many isolated coding exercises.