At first, I thought it was suspciously similar to Gyossait... then as I played, I finally realized it revolved around a very different theme and created a very different and ultimately, less cynical (though no less dark) world.
What amazed me is the attention to detail regarding the endings. In particular, it is possible to find a third path regarding dealing with Tanas ; if you never killed and never equipped the halo, you can mash the movement arrow to break free when he try to mind-control your character into joining up with him. This will allow you to seal him away without having to rely on Gomadi's power.
Of course, given the way Tanas speaks in the resulting cutscene, it's very probable this can only be done if you don't kill anything (AKA coming to him pure) and never equipped the halo (thus keeping your character's willpower intact). It's likely that if you used any of the gifts, you won't be able to break free no matter how much you button mash.
I found that both deities were ultimately extremely flawed yet, not as completely dark as they seemed. Both were unworthy of being listened to and did horrible things yet weren't exactly as clear cut evil as one might expect ; Gomadi was trying to salvage a world savaged by sapients who proved unable to keep from destroying themselves and the world and in trying to do so, inadventely become just as much of a monster as those he seeked to purify. Meanwhile, Tanas wished to preserve the spark of freedom in all sapients even to the point of self-sacrifice but was unable to keep his ego from overwhelming his empathy, turning him into the monster Gomadi accused him of being.
I felt that both being flawed also helped make the dilemna meaningful ; if both had been pure evil or if one had been pure good, it would have spoiled it. Neither were pure monsters, they were ultimately just what everyone in the reviews call them: douchebags.
Regarding the gameplay, I found that it gets much easier to control if you keep in mind the momentum of your character. Compared to Gyossait, a game to which it is often compared, it must be noted that the jump mechanics are actually significantly better though they both share the 'hit ceiling, plummet like a stone' point. Regarding foes, dealing with them become a lot easier once you realize they don't truly "exist" unless they're on-screen ; foes stop in the last position or action they were when scrolled off-screen, even pausing mid-telegraphing for attacks. Likewise, making sure to observe foes and note when they flash is vital to avoid them.
Spiders can be quite problematic, surprisingly more than the executioners but you can easily jump over them by jumping in the opposite direction of their movement ; their very swift movements will carry them under the player character even if in halls with low ceilings.
Likewise, dealing with executioners is easier once you realize that they will never harm you physically, only through their gun, and that they never turn around ; you can easily run or jump through them and stand behind them to avoid their gunfire.
Unlike in Gyossait or most of Amon26's games, Tanas and Gomadi are not capable of defending themselves so the game doesn't really have bosses ; Tamas may attempt mind-control if you lack the halo but otherwise, you don't really fight either of them. Gomadi zapping you if you walk up to him "tainted" does not count.
Graphically and musically, the game is top-notch. It does have a style similar to Gyossait but the metallic, futuristic style of the game (wherever Amon26 has much more organic-styled environments and monsters) and the fact that it doesn't bombard you with surreal, nightmarish imagery like Amon26's games ultimately set it apart. Musically, it has more 'real' music than Amon26's games, which is both a good and bad thing varying on the point of view and the scene in particular.
I felt the game was excellent, ultimately.