In my opinion, this CSS code is the best solution available. (It's worth mentioning that Bootstrap4 is used in the following script)
<style type="text/css">
.my-style {
border-radius: 8px;
width: 120px;
box-shadow: inset 0px 3px 1px 0px rgba(83,154,197,1),
inset 3px 0px 1px 0px rgba(83,154,197,0.4),
inset -0px -3px 1px 0px rgba(0,73,140,0.8),
inset -3px 0px 1px 0px rgba(0,73,140,0.3);
}
.my-style:hover {
box-shadow: inset 0px 3px 1px 0px rgba(83,154,197,0.5),
inset 3px 0px 1px 0px rgba(83,154,197,0.2),
inset 0px -3px 1px 0px rgba(0,73,140,1),
inset -3px 0px 1px 0px rgba(0,73,140,0.5);
}
</style>
<button type="button" class="btn btn-primary my-style">GAME</button>
Another option is to use the image itself as a button:
Embed image in a <button> element