I'd suggest to add a page block instead... with this block you will not have to edit game.php (which is a part of the script's core) each time I release a new version of the script.
The block is pretty simple: it must be PHP, active on game page only (all in terms of the "new page block" tab inside admin cp), filename is up to you, block_gameinfo for example (to be sure there is no block with the same filename check the /content/blocks/ folder contents in your ftp program), title, max elements, comments and sorting fields will not be used so enter anything in them.
The code is almost the same to one you know from the original post:
<?php
$tpl->assign('INFO_PLAYS', $gameres['plays_total']);
?>
So, the block itself is ready and assigns the number of plays to "INFO_PLAYS" macro which should be placed in the form "!INFO_PLAYS!" somewhere in the page_game.html template (you'll find it under the "pages" tab in admin cp.)
One more thing: inside this block you can assign all other values to appropriate macros to show on the game page, for example plays_today, etc. to see the entire list of variables inside $gameres array open your database in phpmyadmin and check out the <prefix>_games table's structure.
Also I'd suggest you to use prefixes in all macros you'll assign (different for different blocks, INFO_ in my case) - this will prevent the blocks from overriting other blocks' macros.