Pretty much every platform in this gaming generation has had a downloadable Bomberman title. The DSi hadn't yet, so Hudson must've figured "Why the heck not?" and made yet another one.
As with all other downloadable (non-Virtual Console) Bomberman titles, this is strictly a multiplayer affair - there is no adventure mode, so the only thing you can play is the franchise's famous battle mode. The concept is still the same as ever: you're thrown into an arena with up to seven others and the objective is to blow up blocks to get upgrades for yourself and your bombs and blast your opponents.