You can play it on the PC platform, just downloading the game (.swf) and the Adobe Flash Player emulator, when uploading your career you must mark as (PC) on the platform.

Gunball: Emperor's Revenge (In Adobe Flash Player) | Game with Emulator (PC)

Play game using the Supernova player for easiest results, when playing with this player, you must place on the platform: Web when uploading your career.

Gunball: Emperor's Revenge (on Kongregate) | Game on the Web

The easiest (imo) way to play flash games like this one.

Supernova Player

ManuelGamesYT1550

Ruminino

Gunball: Emperor's Revenge

ThinkCash6

USA / NTSC

You can now run this game and upload your races, I leave you the link of the game, if you want to install it, in the (Guides) section, you will find more information :)
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https://www.speedrun.com/gunball_saves_christmas
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Name	Manager
Gunball: Emperor's Revenge (In Adobe Flash Player) \| Game with Emulator (PC) by ManuelGamesYT1550	ManuelGamesYT1550 3 years ago
Gunball: Emperor's Revenge (on Kongregate) \| Game on the Web by Ruminino	Ruminino 12 years ago