Shienryu

Shienryu is a shoot-em-up developed by Warashi for the Saturn released in 1997. The spiritual successor to Daioh, it features much of the same mechanics; however, it also features a hidden multiplier mode provided you have no lives remaining and are using the missiles as the main weapon. Also new are the so-called LED items, which randomly drop from any ground or flying enemy that can hit the ground.

PearlASE masterfully demonstrates the hidden multipler mechanism, obtaining a total score of 156,391,150 points whilst not abusing an infinite scoring pattern on the final boss, as it doesn't have a timeout mechanic. Said pattern can be viewed here.