Always get this game recommended by Steam on the Storefront and thought I'd just try it out. As much as I personally didn't mind the game at times, I cannot in good faith recommend it willy nilly in general.

Getting the major issue out of the way, the game is poorly optimized. Absolutely serious complaint in regard to game enjoyment. One of the worst performance that I have encountered in recent memory as far as this genre is concerned. I've ran it on a more than necessary 4060 laptop, Legion Go and a desktop with a 4090 + beyond reasonable specs to make sure I wasn't overexaggerating/giving false info and the frame rates simply drop way too frequently during gameplay to the point where it is visually annoying due to stuttering. Playable? By a very loose definition of 'playable', yes. Enjoyable? Not really. I'd love to say that it isn't a big deal, but it is truly unacceptable given that it isn't even a fully realized 3D game.

Gameplay is simple. Pick a character, move around the map shooting enemies to survive until the boss arrives and pick up various weapons/abilities/powerups along the way. Weapons are slow starting off and more often than not you'll rely on RNG to obtain decent weapons to complete the map (a.k.a you will unfairly lose a lot on higher difficulties). Most weapons loop their sounds and it can get annoying/jarring after a while hearing the loop. I ended up muting everything and listening to external audio while playing. In game music isn't particularly awful, but it does get repetitive.

Translation is particularly egregious. Very broken English with typos, but I didn't really care all too much since I was more interested in the gameplay rather than the nonsense story. Didn't skip any dialogue so far, but there's a point where you read what is written in this game and wonder why there's even a story. It's just nonsense. At best, you can have a laugh or two from the weird translation into English.

Audio is bad. Sounds loop and characters repeat one (or two?) voicelines if I remember. I also had a bug while adjusting audio where sounds wouldn't actually increase or decrease properly. Not very good overall.

Artwork is not good in my opinion, but that's probably because it looks a bit strange from my perspective. Characters are detailed in some areas, but certain parts are not very detailed and it sticks out (and not in a good way). They are also not very likeable in my opinion, but that depends on individual tastes.

And of course, the eroge part of the game has to be criticized, even if I didn't care for it. I found it very, very, very strange. I can't put my finger on it, but the content is just weirdly executed. Usually eroge is the main focus/incentive of these games, and I wasn't finding myself very enthused about any of the scenes. After you've played a decent amount of quality eroge visual novels or similar games with a little bit more effort put into them, these scenes come across as 'amateurish' or 'boring' unfortunately. I just clicked through them and never looked at them again. That's how bad I thought they were. Take that as you will. I will say that the DLC 'scenes' were much better than base game's offerings, but still came across as 'not that great' overall. To each their own.

Finding something positive to say about the game is very difficult/near impossible. From performance to audio issues, to artwork and clunky gameplay, there is some sort of underlying issue that is a problem. I can't think of anything positive other than that the game scratches the itch if you wanna play this style of game, but not spend too long on it. Like, pick up and play for a few minutes to pass the time.

Again, do I recommend Isekai Frontline? Sorry, but NO. Absolutely not. Nothing against the game itself, but the performance and overall sloppiness of pretty much everything within the game makes it difficult to recommend to anyone due to the fact that you are spending money on a subpar product that is very much in need of optimization. Sloppy is the best way to describe the game. I think if the game went in a different direction with a little more effort put into it, it would have been at best a decent sidestep to the genre, but clearly that is not the case. If you still find yourself wanting the game despite all these issues, by all means go for it. Just curb your expectations and remember that you are spending money for a subpar product, even if it is 'cheap' or 'just a few dollars'.