This game man, they clearly cared more about getting players to spend their money on arcade tokens... I got to the last level and the game really shows a lot of bullshit design in it's second half.
Firstly the damage enemies deal is absurd - you can be killed in 4-6 hits (or even 2, some bosses hit that hard) and there are a lot of enemies for you to kill, plus you have to spend some time comboing their asses, but they can just close in and slap you for full damage in single hit.
Secondly enemies have amazing reaction and attack properties, sure you have some time to attack first but it's a short window, 80% of enemies attacks have no delays and come out very fast so you can't even react to them (there are aliens that spit acid at you from half a screen away and it hits you for 1/5 of your health, this attack comes without any warning), advanced enemies have more reach than you and even faster reaction, it's especially noticeable at second boss. Sometimes I get hit out of "dash" moves that allow you to cross the entire screen at a second, but enemies still react fast enough to hit you out of them.
Thirdly grab mechanics are annoying, you should be familiar with it's principle - you get close to the enemy and you grab them, but when you are fighting off hordes you don't fucking need that, the moment I accidentaly grab somebody I'm instantly hit by other enemies because grabs don't give you any protection (oops 1/5 of life gone). There's also a problem when there are a lot of items on the ground and you character starts picking them up instead of attacking the enemies, since you also pick up items by pressing attack button, argh.
And lastly you can't run (although dash moves allow for great mobility) but what really sucks is that you can't travel Z axis at great speeds, you can only walk and it really fucks you up in battles, it's especially insulting that some enemies can do that.
Encounter design is fucking excellent as well. The game tries to own your ass as early as level 2 (it's only going to worse from there) the boss of this level is a lighting fast motherfucker that outranges you, dashes across the screen (and jumps you out of the screen) and kills you in 4 hits, but it's not really a problem compared to what comes next. At level 4 they introduce ambushes, basically enemies charge at you out of the screen, unless you know it's coming you are going to get hit (that's 1/4 of your life) and still have a horde of monsters to kill. The fucking alien queen - the boss of that level is pure retardation, I searched for some videos where people that are better than me beat this fucking game - nobody kills that boss legit, because it's impossible. She attacks at both directions simultaneously and you can't even sidestep her attacks because they have such an amazing reach, lol. Some guy killed her by using a disc, but it's RNG. Later levels have same shit but at greater quantities, although bosses aren't as retarded. I rage quit final level though, didn't get to the boss, might do it later.
Alien queen abuse - stand on the crates so she can't attack you.