Sure, here's an example of a simple fighting game implemented as a single HTML file using JavaScript, enclosed in `` tags:
<br><br>
<br>
<style>
#player1, #player2 {
width: 100px;
height: 100px;
background-color: red;
position: absolute;
}
#player2 {
background-color: blue;
}
</style>
<div id="player1"></div>
<div id="player2"></div>
This game will simulate a simple fighting game where two players can move left and right using the arrow keys (for player 1) or 'a' and 'd' keys (for player 2) on a smartphone. Pressing the up arrow key (for player 1) or 'w' key (for player 2) will trigger an attack animation if the players are close to each other (within 100 pixels). The players are represented by two colored boxes on the screen.