Sure! Here's an HTML file with a simple sandbox game that implements the portal gun features you mentioned:
To play the game, simply save the above code in a `.html` file and open it in a web browser on your smartphone. You can use the WASD keys to move the player and the spacebar to place a portal. The game renders a player (a gold square) and two portals (orange and blue). You can place portals by tapping on the screen. Enjoy your sandbox game with portal gun features!