This game pleasantly suprised me.
It plays similarly to games like binding of issac or nuclear throne, being a top down shooter with a large inclusion of roguelike elements.
The gameplay involves doing a variety of differing quests in order to complete levels, while collecting items to make yourself more powerful. Some examples inclide destroying the summon pillars, collect x amount of items, and destroying waves of enemies quickly to weaken a boss. Combat is that of a twinstick shooter, focusing on movement while attacking surrounding enemies. Each level is procedually generated, and the player progresses over a world map aiming to reach the end through beating each stage. Death in the game without special items requires the player to start over in the chapter. In online co-op the players have a shared pool of 3 lives, but if that pool runs out, then they lose.
There are various classes in game which each have their own unique abilities and rampage effects. The beginning class has dodging, a sort of fire mortar, and the rampage involves summoning an ally to your aid. Later examples include the ability to summon stationary totems to deal damage, or sacrificing ones own health to deal damage. The inclusion of the class abilities gives a reliable way to deal with challenges without having to worry about your luck being down, and gives the player a fairer chance to survive without item drop luck being a trouble(compared to other games of the type)
The game includes more customization then just class though, also including various unlockable and upgradable pins which modify starting stats, many unlockable masks (for visual difference only), and a levelling system which gives minor stats through leveling. (Though this same leveling also is required to unlock use of the pins). The leveling so far hasn't seemed to imbalance the game, as it has remained difficult throughout. As well, it includes a variety of difficulty levels which unlock as you beat each chapter. Each difficulty level seems to add more hazards, as the one right after the normal difficulty makes enemies harder, whlist adding a chance for enemies to drop bombs after death (and there are about 3-5 more difficulties after that).
There are many items in FMR, with a variety of upgrades, weapons, and consumables. There are about 12 weapons, each weapon with a unique projectile. Each weapon not only has the base projectile type such as a beam or a boomerang style poison cloud, but also includes randomly chosen bonuses, including extra projectiles, bonue damage, and extra charges. Though each weapon has a certain amount of ammo before it runs out, each weapon can be stored in the inventory for later use. All relics and inventory items can be swapped out for others at any time for other ones, though as well the player is limited to a max of 5 relics and 5 inventory items after obtaining upgrades (the player starts with base 2 relics and base 3 inventory).
Relics (also known as mojo's) are the primary items for upgrading your character. Their effects vary from the base mojo giving base stat upgrades such as health, damage, crit chance, or a percent chance of a homing missle, to the unique mojo's which give larger bonuses as well as unique effects, such as heal on critical hit, or enemies summoning a black hole on death. The inventory can hold weapons, relics (for later use) and usable/consumable items. Usable items are more often one use only, but others have a timed recharge. The inventory items have a large variety, with such items as a temporary spread shot potion, a disco ball that distracts enemies, a pipe which summons an allied cannon or kamakazee pack, and a passive knife which permanently buffs you once you land the killing blow on four elite enemies.
There are also coins for shop items and pin upgrades, and tokens for unlocking classes and masks. A feature which does bother me a little is the fact that coins are continuous between games, meaning that players can purchase all of the items they want after upgrading all of their pins, and don't have to worry about money like in games such as issac. I'd rather prefer that coins be added up into an upgrade bank after each run, but have each run start off with no money.
Enemy variety is fairly big. Though each stage only has a certain amount of differing enemies, there are many stages to choose from, such as swamps, lava pits, caves, dungeons, and pipe ridden distilleries, each with different enemies. Each stage also features background secrets which grant items, and each stage has their own different looking secret (though a little more variety in the secrets for each stage would be appreciated). Not only is there a variety of base levels, but as you go through each chapter, a larger variety of quests and areas are given, and though the first chapter may lack in some variety in quests at first, progressing certainly causes the game to open up. The game also features boss encounters which do seem to change in some encounters, but since I've played some chapters more then otherss, I don't know which have changing encounters. Nonetheless, the bosses were challenging and fun, and each one functioned differently.
Aside from the main levels, there are also side areas accesible from the map, such as shops, mojo mixers, shrines, and challenges, all with very different ways of functioning. The shops are what you would expect, allowing one to buy and sell items. The mojo mixer is a unique area of incredible value, which allows the player to combine two mojos (upgrade relics) into one upgrade, saving precious upgrade slots, and allowing one to equip more relics. The shrines have a variety of effects, some being purely positive, while others end up being more risk/reward. The possible effects of the shrine depend on the class the player chooses, and in online co-op, all of the different players classes are chosen from for the possible shrine effects. As well, in online co-op, shrine reward items are distributed depending on how many players there are, so that other players don't get left out. The challenges are varied as well, ranging from destroying a mini boss in someones nightmare, to fighting off enemy skeletons to defend friendly zombies.
Right now there are only base 4 chapters, a survival mode, unlimited survival, and a generated daily quest (similar to spelunky). Each chapter is procedually generated in both the selected map layout, and the individual stages, and though I haven't yet tried it, I would assume the survival would include some sort of random elements as well. Though 4 chapters doesn't seem like a lot, they have taken quite a bit of time to get through, plus I haven't yet tried variety of other difficulties, or the survival mode. As well, if you enjoy the leaderboard focused daily challenges in something like spelunky, then the daily challenge will likely interest you.
I haven't tried the local co-op, so I cannot speak for whether or not it is very different from the online co-op, but the online co-op is a blast, though some of the mechanics may put some off. Players have a shared 3 life pool, and once a single player dies after they are all lost, the the run is lost. As well, players must revive eachother when they fall. A player can obtain other ways of revival, but there is no way to regain shared lives to my knowledge. Players must share items they come across, including weapons, upgrades, items, and coins. I personally like this fact, as it ecourages a team sharing of items to help with other players builds, but there are a few downsides. The inventory and relic upgrade slots at the time of typing cannot be dropped, and players can accidentally pick them up, even if they have reached the maximum for that slot type. As well, coins are not shared, and cannot be dropped.
Overall, it's a wonderful game in my opinion. I absolutely reccomend it.