The influence from games like Gunstar Heroes, Alien Soldier and other Treasure games is clearly present and admirable, but it lacks a lot of what makes those games fun and interesting from both a gameplay and thematic level. In terms of gameplay, it's just your standard run-n-gun. I heavily dislike the Heat mechanic as I don't feel it really adds anything but frustration. How is holding the button down any different than mashing it? The stamina bar makes more sense with limiting your dashes, but I don't believe they needed to be linked to multiple jumps as well. The level design ranges from decent to atrocious. The screen will be littered with enemies and projectiles with no real means of dodging any of it, and more often than not amidst bottomless pits. The bosses aren't anything to write home about, as most of them are homages to other Treasure bosses but, again, nowhere near as fun. There are sporadic vehicular segments that, may seem fun and interesting at first, but quickly dive into another annoyance once you realize they limit your movement in ways to make it harder to defend yourself by rendeding any option built upon stamina completely useless. It's hard to tell what's more frustrating though, the gameplay or the writing. Even though some of the better Genesis games opt for pure visual storytelling, Spectacular Sparky decides to switch things up by including incredibly cringeworthy dialogue that wouldn't feel out of place from the "Epic Bacon" era of the mid 2010s internet. Not only is the dialogue unfunny, not only is it heavily frequent, breaking up the flow of bosses, the game is fully voice acted, and the vocal direction isn't doing the writing any favors. Visually it's decent, the main character has a charming design as do some others, and the backgrounds are impressive. The soundtrack is also very good, and does a great job at capturing the upbeat energy of a Genesis game.
Other than that, I unfortunately don't have a lot of great things to say about Spectacular Sparky. It took me around 4 hours and if it wasn't gifted to be I definitely would have refunded it. Anything you're interested in here you can get out of a Treasure game, Metal Slug, Cuphead, etc., and I can't reccomend those games over this one enough.