Can WordPress Use Index2.php?

On my website there is currently a splash page which allows users to select to go to the main site or to our forums. This page is called index.htm.

I tried to install WordPress into the root but now when users go to our site index.php is taking precedence and is becoming the default page. Is it possible for WordPress to use a different name, such as index2.php? I’m trying to avoid installing it to subfolder.

I’m sure there is a way but I tried to simply rename it and it screwed up the formatting.