Adobe Flash WAS a multimedia software platform used for production of animations, rich web applications, desktop applications, mobile apps, mobile games, and embedded web browser video players. In 2020, Adobe ended it's support for the application, and blocked flash content from running in flash player since January 12, 2021.
This doesn't mean Flash is dead, however it does mean it's prevalence and popularity has fell in recent years.
Heyuri still uses flash to a certain extent, and there have been OC made with flash. Due to it's novelty within the circle of the old internet, it is revered and popular within the community. Multiple flashes of OC have been created, and there was even an /f/ board at some point. As such, flashes are a staple in the commnuity and it is always welcomed when a new flash is made.
Multiple flashes have been planned, however due to drama, they never came to fruition.
If you plan on becoming an epic heyuri oldfag, you should accustom yourself to the culture surrounding flashes.
Ruffle is a flash player emulator created in the Rust programming language. It runs as a standalone application. The issue with it, however, is that it is new and very buggy, and not alot of websites support it just yet. It tends to be used as a flash alternative, however if you have an older installation of flash this is unnecessary as the application can still run on your computer.
Macromedia Flash 8 (2005) with serial: https://up.heyuri.net/src/816.7z
Macromedia Flash MX (2002) with keygen: https://up.heyuri.net/src/815.7z