This is the grey area. Emulators themselves are 100% legal (courts have ruled that they are fair use). However, downloading a ROM of The Simpsons: Hit & Run from an online emulator link is technically copyright infringement because you are bypassing the need to buy the game.
That said, since the game is abandonware (no longer sold by the rights holder), copyright holders rarely sue individuals for downloading 20-year-old games. The risk is low, but it is not zero. If you own the original PS2 or GameCube disc, you are legally allowed to dump your own ROM. simpsons hit and run online emulator link
Link pattern: oldgamesdownload.com/the-simpsons-hit-and-run/ (They occasionally feature a "Play Online" button)
Verdict: One of the more reputable retro sites. They usually offer a downloadable version but have experimented with in-browser Java/Flash (now obsolete) and newer Web emulators. Their browser version is slow and lacks save functionality. This is the grey area
If you want the best "online" emulator link experience (even though you play locally), follow this guide: Set Up the Emulator
If you own a physical copy of "Hit and Run," you can use an emulator to run it on modern devices. Here’s how:
Set Up the Emulator
Install Necessary Patches