I've been a 2D shooter fan for decades. Konami, Cave, Capcom, Taito, Raizing, I've played all of the arcade classics. I've completed a ton of doujin titles as well, along with a multitude of random one-off games by guys nobody would ever care to know about. Basically, I know the genre well enough to spot what works and what doesn't within minutes.
Let's start with the controls. This game is controlled with the analog stick, which is kinda strange. Initially I thought it was inertia but it's mostly an odd design-decision. Personally I'd rather just have two speeds, instead of a half-dozen. Also, the ship moves at different speeds depending on whether the player is moving horizontally or vertically (WHAT?). This can be fixed in the options.
When you play a 2D shooter, you expect to dodge a lot of bullets. Everything just seems to be thrown around at random. It can take awhile for everything to click. Some bullets move around, I mean yes they move because an enemy just fired them at you, but they also swirl around slightly. In-game it looks really disorientating.
Psichodelya uses a shield system. You can switch between a red and blue ship. By doing this you absorb like-colored bullets, but opposite-colored will kill you instantly. Okay, but this shield can only take a few hits. It won't last long if you fly into a mess of bullets. The strategy is to figure out which bullet-spreads you're liable to have trouble with, and switch to the appropriate shield. It's better to just avoid bullets entirely, but there is a buffer of sorts. The power of the weapons is influenced by the color of your ship and the enemy's. Naturally, you do more damage when firing on opposite-colored ships.
Unfortunately this system is a wasted opportunity. The shields look like a mechanic that could be expanded upon, by creating a risk/reward system. Maybe instead of limited shields (that resemble lives), how about making the shields rechargeable? The like-colored bullets the player catches in their shield could turn into extra points. The bullet patterns could be arranged to facilitate this design-decision, leading to all sorts of creative scenarios.
For the most part, enemies are arranged in a very un-natural manner. Larger ships tend to approach in pairs, while smaller/weaker ships make occasional appearances. It looks too organized. While ships differ in fire patterns, their never seems to be any deviation in how they make their appearance. Ground targets such as turrets and tanks would have added to the diversity and made for better stage-flow. Like the Dodonpachi series, this game uses a shot/laser setup, but the shot rarely sees any use due to the lack of weaker enemies.
Psichodelya wears its influences on its sleeve. While it's nice to know this game has its heart in the right place, it doesn't really do anything different. When a game has too many similarities to an older yet highly-regarded title, its weaknesses tend to stand out. At this point I'd rather the newer game try more original ideas, even if they don't really work. Psichodelya takes inspiration from Dodonpachi, Ikaruga, and Dimahoo, but it lacks the core elements that make those games great.
On top of everything else, this game just looks cheap. I won't comment on the art-direction, because that's all relative. However, the graphical effects, the ugly bullets, everything else looks slapped together. It's cohesive only in the sense of being completely and utterly bland.
After a shockingly bad first impression, I can sorta see where this game is going, but it's not there yet. I'd call it an inferior clone of a Cave shooter, but that would be giving it too much credit. The doujin community has put out a ton of shooters in the same vein, and they tend to be of decent quality. Psichodelya is simply too derivative and too boring to be worth the time.