Final answer:
To activate debug mode in Sonic 3 and Knuckles on a computer, press F3 after holding A and selecting a level. If this does not work, you may need to check the emulator's settings for the correct key. Key mappings can vary based on the emulator's configuration.
Step-by-step explanation:
To activate debug mode in Sonic 3 and Knuckles on a computer, particularly when playing through an emulation site like Gameslol, the correct key to press after holding A and selecting a level would typically be F3, based on classic Sega Genesis emulators' functions. However, because key mappings can vary depending on the emulator and the way it's set up on websites or different platforms, if F3 does not activate the debug mode, you may need to check the emulator's settings or controls configuration to find the correct key. In some emulations, the 'Start' button, which may be associated with Enter or another designated key on the keyboard, is used in conjunction with other buttons to activate cheats like the debug mode.
To activate debug mode in Sonic 3 and Knuckles on a computer after holding A and pressing a level on Gameslol, you need to press F3. This will open the debug mode menu, which allows you to access various options and features in the game. From there, you can use different keys on your keyboard to perform actions and manipulate the gameplay.