Everyone always brings up Mushihimesama, DoDonpachi, or Death Smiles while discussing CAVE games, entirely ignoring Espgaluda, which is a complete crime against humanity.

Here's the gimmick: You have two shooting styles: the primary one, which is just your usual, straightforward type, and the secondary one, which activates "slow mode." While in slow mode, enemy projectiles will become much slower, making it easier to avoid them, and your projectiles will deal significantly more damage. The catch is that in order to activate slow mode, you'll need to collect emeralds, which can only be acquired by destroying enemies with your primary shooting type. This forces you to use your primary shooting style most of the time, destroy as many enemies as you can, and get familiar with every stage, using slow mode only when necessary. In fact, abusing slow mode will lead to the exact opposite effect: enemy projectiles will get much, much faster, making them almost impossible to dodge. This mechanic has so much depth and allows for so much experimentation that it alone makes subsequent playthroughs worth it. I'm still discovering little tricks. 

On top of that, its action, coreography, and enemy projectiles are all so well crafted and thought out, so above much popular shmups that it makes me wonder... Why does this one not get the praise it deserves? 

The music is also fantastic. I'm not a big fan of techno but shit slaps.