>both settings have mercenaries as the core of their setting because standing armies are too expensive
>both settings have fusion powered vehicles
>both settings have combined arms
>both settings use laser weapons as a predominant form of weaponry
>the primary vehicles in both are noted for their redundancy and ability to continue acting and moving even with damage
>both settings are essentially historical war stories with a futuristic coat of paint
>both settings have the same reason why aircraft aren’t dominating the battlefield
Honestly Hammer’s Slammer could easily be an alt-universe of Battletech where people just acted slightly more rationally.