I've been working on Athena Crisis for about two years, and full time for the past 9 months. The game is entirely built from scratch using React and CSS without a game engine. It runs anywhere, including the Steam Deck. You can even use a gamepad on the landing page to play!
Previously the landing page had a video of the game but my goal was to always just put the actual game on the website. I merged the landing page into the game's monorepo, added the game's React components, and boom – the video was replaced with a playable version of Athena Crisis.
Of course, the real game has tons more features, but the landing page now always runs the exact same code as the actual game – including assets, the AI, and the UI/UX – and it is pushed within 5 minutes as the actual game is being updated live.
I frequently talk about the tech behind this game (see this React Summit talk about "How Not to Build a Video Game": https://www.youtube.com/watch?v=m8SmXOTM8Ec ) and I'm planning on open sourcing as much as possible in the future.
But actually having a demo directly in the middle of the action embeded in an iframe of the landing page is quite neat. It blends properly with the rest as well, so actually well done.
Some feedback: - Demo plays music. If the user clicks the purchase button, a new page opens which also plays music, this can be quite unpleasant as they are both playing at the same time. - Personally I like the art of the game, including the pixel art character faces, but I don't like the banner. The banner feels like it was drawn by a teenager discovering photoshop with a book "learn to draw manga style in 2 hours" – That might be a bit unfair and I'm sure it was a lot of effort, but a lot of details make it feel amateur-ish in the wrong way, in particular the most central character and its face. Have you considered using the same pixelised style that you use for describing each character bellow? - on firefox the character faces overlap with the text on "Create your own maps..." (Firefox, Mac OS, very large screen)