This is a game by Armor Games and unlocks more features if the AG Save System is used. Whenever I click on the option to use that system, it redirects me to my profile on Armor Games. This game is not available here and I am using a different browser to play it. So, can anyone guide me about how to use that system?
Unfortunately Kingdom Rush Frontiers isn't playable on ArmorGames.com anymore as it uses AS3 (ActionScript 3 for Flash) and the emulator we offer (Ruffle) doesn't support that yet. The game expects to receive an authentication token through its Flash variables (a property you can use to pass data to the Flash object on the page) which it then uses to make requests to our back-end for authentication, online saves, achievements, leader boards, etc. We still support the back-end for the game but since it's not hosted on our site you won't be able to use it.
We hope to bring back the Kingdom Rush games in the future and Ruffle has been making advancements toward AS3 support but emulating Flash is an enormous engineering challenge.