People have been making crossovers for years, from Jetsons meet Flintstones to Alien Vs Predator.  And as much as movie and gaming companies make crossovers, they're dwarfed by the shear amount fans make.  Things like:  Super Mario Bro's Z or MLP meets, and the hundreds of pictures you find on Deviant Art just scratches the surface.  It makes sense, crossovers are a way you can combine things you like.  A crossover goes beyond a reference, having two different things put together into one piece of work.  However this can be difficult to do properly, especially when the two subjects are radically different.  A great crossover combines the two while maintaining the essence of both the originals.  An OK crossover has little to no essence of one side.  A bad crossover loses the essence of both the original pieces in the processes.  An example of this for me is Pokémon Harvest Craft.  The bigger the work the harder it is to get a good crossover, a picture is fairly easy, a video is harder, and a game is the hardest.  So a Touhou and Mario crossover is quite the challenge.

     Touhou is a Bullet Hell series known for it's insane difficulty and awesome music.  Mario is a platforming series known for it's simple game-play and cool power-ups.  While Mario can be challenging, like in the Lost Levels or Mario Maker, it is for the most part rather easy.  These games have very little in common game-play wise and so trying to combine these two may seem like lunacy, but the greater the challenge, the greater the reword.

 

     Graphics (8):  Considering when I first saw this game I through it was just going to be a texture hack, I was still surprised by how good the graphics look.  The levels look very well made, the textures they used work well with the level themes.  The enemy sprites look really neat; from the maid fairies, flying Yin Yang Orbs (yes, that's a thing), to the bosses sprites.  To top it off, the effects used look good and combine well with the game, notably the darkness effects.  What holds this game back from being any higher is that not all the sprites were replaced and so you'll see Hammer bro's, and Magikoopa in the latter levels.  Beyond that some of the boss sprites didn't work as well as the rest in my opinion.

 

     Sound (9):  I wouldn't say Mario Music is bad, but it's definitely not the stuff I would usually put at the top of my list of best soundtracks either.  Mario's music gets the job done, it's main appeal is mostly out of nostalgia, especially the earlier games.  The soundtrack for this game consists pretty much entirely of music from Touhou, so naturally that means it's really good.  Love Colored Master Spark, Immortal Smoke and other classics are all in this.  Even some bonus ones like Bad Apple, Beloved Tomboyish Girl, and a few I don't want to spoil.  Does it deserve a 10?  Maybe, but I didn't listen to the music all the time so I don't think I can give it a full 10, but it is an easy 9 on my part.

 

     Addictiveness (5):  When I started the game I really wanted to beat it, but once I beat the game, the post game, the post post game, the post post post game, and the super secret post game content I had no need to go back to it.  It's something I wanted to see through to the end but not something I want to go back to after the fact.  There might be some secret secret post game content, but I'm not going to try and find it.  The game always gives you something more to want to do that seems just in reach until the end; and for me it's something that I felt myself want to reach.  While the difficulty (I talk about that later) may be a turn off to some people, it didn't really detract from my experience.

 

     Story (6):  There isn't much story and the story that is here isn't very complex, Mario goes for a walk, and ends up involved in the entire Imperishable Night incident.  There's a bit of dialog before almost every boss and a boss at the end of (almost) every stage.  While it's defiantly not Shakespeare, it wasn't horrible either, and I did really like some of the lines.  I may not be a huge fan of how Mario was portrayed in this game, but at least it's better than the Philips CDi Version.  I did like some of the encounters in the bonus stages.  This game was made sometime after Touhou 11, but probably before 13, which is sad because I would have loved to see Mario interact with Mamizou considering his past dealings with tanuki.  Also I'm a little disappointed Perfect Cherry Blossom didn't get ANY representation in this game, I was kind of hoping Yukari would be the Secret boss, but sadly, no, she is not.  She might be a Secret Secret boss, but I'll probably never find her if she is.

 

     Depth (5):  There's 6 main stages and an extra stage just like a regular Touhou game.  However to unlock the Extra Stage you need to get the good ending which requires you to find a hidden exit and then beat a harder final boss.  There's also some post game content, and some post post game content.  And some Secret post game content.  And maybe some Secret Secret post game content.  While other Mario Games may have more to do this game, this game defiantly gives you the feeling of a lot to do.

 

     Difficulty (7.5):  I couldn't decide whether to rate this a 7 or an 8.  If it was just the main stages I would go for a 7, but including the bonus content it leans more towards an 8.  So I decided a 7.5 best represents this, a normal run isn't that hard but if you want to 100% the game you're in for a serious challenge.

     The main challenge is that there are no lives, no continues, and no saves.  When you die, you have to restart the game, so it works like a classic NES game.  For the most part I'm OK with this, it's similar to a Touhou run.  However, I do think that certain things should stay unlocked after you unlock them, like the Extra stage and such.  It took a TAS about an hour to beat the game, and if you die even once, everything you did up until then is gone.  That said, the game however isn't totally unfair, it gives you a rather generous life bar similar to Metroid.  You have in essence 5 life tanks, each of which have 99 health, and when you get hit you lose 20 health.  Collecting health pickups and completing boss phases will give you 20 health.  Since there are no lives the game gives you a new use for coins, you can trade them in the hub level for health pickups.  Aside from one true bottomless pit (you should be using the cloud) and one crushing point there are no instant kills in the game, so that defiantly helps.  When you fall down a pit normally, you bounce out and take damage instead of dying.  There are 3 power-ups in the game, but two are localized to certain stages that use them, and the other is a secret reword.  The game is definitely hard, but for the most part it stays a fair kind of hard.  It doesn't use traps that catch you unaware, or have hidden block jumps, and there are almost no blind jumps.  For the most part, if you reach a point that can soft-lock you, it gives you a reset point to try again.  The game has a lot of things you have to dodge, especially during boss fights, but the difficulty is more in doing it rather than figuring out what to do.  And with your health pool you have some room to mess up and still stay in the game.

 

     Overall (7.5):  This is overall a very well made game.  The graphics look good, the levels are well designed.  Each level has it's own unique feel and mechanics to it.  The sprites work well for the most part, and it feels like you're in Gensokyo, and the music is Awesome (Obviously).  The game does a good job of combining Touhou and Mario, keeping aspects of both, but making something new as well.  You go around, jumping, dodging, and stomping on enemies.  In boss fights you go through various phases each having their own bullet pattern you have to weave through in order to hit them, and often you have to use their attacks to jump high enough to hit them.  The game had a lot more content than I thought it would and I enjoyed playing through it.  What holds the game back is that considering the content you have to go through it all gets reset on death.  While I enjoyed the game I had to abuse save states to get to where I did, if you tried to do this without save states you're in for a real challenge.  I enjoy a decent challenge but it's a bit beyond my tastes.  But if you enjoy challenging Mario games then this might be for you.

     This game is like mountain climbing without safety equipment.  Whether or not you succeed is pretty much entirely up to you, there's no safety net holding you.  The farther you get, the more painful failing becomes, but the greater the feeling of accomplishment is when you overcome it.  While it gets trickier the farther you go, your goal is always in sight and it never gets too hard to handle.  And while it's certainly not something for everyone, for the people who like to put it all on the line it's perfect.