Why Does My C++/SFML Game Work One Day and Break the Next?

For a game, check whether movement and cooldowns depend on the frame rate. Use elapsed time, such as an SFML clock and delta time, rather than assuming every frame takes the same amount of time. Vsync, battery mode, background programs, and other performance changes can make frame-dependent logic behave differently.

Use the debugger and inspect the program at the exact point where the behavior diverges. Since this is C++, run with AddressSanitizer if your Visual Studio setup supports it; it can catch invalid memory access and other problems. Valgrind is another option on suitable platforms.

Put the project under version control even if you’re working alone. Commit after each working milestone, then compare changes or use git bisect to identify the commit that introduced the problem. Reverting to a known-good version can also show whether the issue is in the code or in the environment.

Dependencies and the environment can change too. An operating-system update, library version, build settings, or changed resource file can affect a program. Still, repeated failures across projects usually point to a recurring bug or an assumption in the code rather than the program simply degrading over time.

C++ programs generally don’t randomly change behavior. Usually either the code or its conditions changed. Common causes include uninitialized variables, undefined behavior, different input values, file contents, dates, or timing. A value that happened to look harmless before may expose a bug on another run.