@model string;

<div class="flexbox">
    <form method="post" action="@Url.Action("JoinGame", "Home", new { gameid = Model})" class="GameArea" style="margin: auto;">
        <h3>Join Game</h3>
        <input type="text" class="form-control mt-4" name="name" placeholder="Enter name" />
        <input type="submit" value="Join Game" class="btn btn-primary mt-4 text-center" />
    </form>
</div>