I really wish I could give CoE 5/5, it's one of the most interesting and most inspired RPG I've played in ages. It's inspired by Earthbound, for one, but also features deep gameplay mechanics both in battles and outside of them while pushing the player to collect more party members in a colorful world with tons of stuff to do. That being said, in its current state, 4 is the best I can give it, mostly because of technical issues but also because of some design choices that I didn't enjoy.
The core idea of the game is you being the Vice President of Earth, going around recruiting citizens to join your party in order to do various tasks such as finding a Moonbucks manager to doing paperwork in order to rescue the president. The humor is very absurd tongue-in-cheek like Earthbound did and there are plenty of direct Earthbound references in there. Most of the core ideas - fighting phone deer and coffee machines in big cities with a team made of a baker, a bug exterminator and your mom is very Earthbound, even if they had no clear references at all.
Not all of the forty party members will join you willingly, they more or less all have quests you have to complete before they get recruited. Some quests are straightforward as finding certain spots in the world, other require you to play mini-games. Some are quite crazy, like having your whole party at level 20, which takes longer the more characters you recruit. I really felt compelled to recruit these characters.
The reason why is that they all have various fighting styles, some more useful than others and leveling them up to unlock their skills is fun. Skills are divided in large categories, some that give energy, some that take it away. Some skills have elemental attributes and enemies/citizens have strengths and weaknesses. It reminds me of Shin Megami Tensei games in some spots. You also can use buffs/debuffs with various strengths and duration, represented by how 'colored' icons are and most of these things stack, allowing for countless battle styles and combos. Of course, nothing is eternal and at some point, a character might not have any more skills to learn, so you might be tempted to use weaker characters because they still have things to learn, and that can make battles harder. Each citizen also has its own gear you can find/buy in the world and the gear has various effects, like turning all damage into fire or increasing your defense whenever you crit.
More so, citizens have talents, which so far is my favorite thing in the game. They are basically game mechanics attached to a party member, and you can level them up to unlock more of the mechanics they represent. Mom gives you tutorial tips, your brother can let you order items from FedUPS, Conspiracy Guy keeps the monster encyclopedia, another character lets you increase/lower the difficulty, another allows you to search trashcans, another gives you fast travel, another lets you train your citizens for X time in exchange of money, the list goes on. I'm not sure if my tune would change after I've completed the game - something I plan to do - because I might be disappointed if the talents overlap too much. I can already see it a bit, there are a few characters whose talent is basically 'buy items' and a few which will be used to progress through the game.
With all that good stuff said... The encounter rate is way too high. There are enemies everywhere and they'll still move while you're in a conversation or something else that locks your movement. The controls on PC are really weird, using ASDW + J/K for basic actions and not letting you change any keys. You can also use the mouse, but it's not quite right. Also if you use the keyboard and the mouse is on-screen, it'll try and take the mouse position while ignoring your keyboard input. The interface is a bit clunky, it would have been nice to know the level of all your citizens at a glance - for instance when you want to send them to school in order for them to passively get experience...
...and the game crashes a lot. I had five instances in a week where the game would just crash to desktop with obscure error messages. I saved as often as I could, but most of the time I had to rely on the auto-save - it saves every time you enter a room - to keep my progress. I also had the game hang on me after starting a discussion before a fight. Some glitches with battle abilities and weird enemy collision here and there... This really took from my enjoyment of citizens of earth, too much for me to claim that I had 5/5 fun with it. More weird is how these issues also occur on consoles, where crashes are - even more - to be avoided at all costs.
Maybe in a few days/weeks they'll have patched everything buggy or messy with this otherwise amazing game, but I'll still keep on playing it to completion, if there isn't a game-breaking bug waiting for me somewhere. If you enjoy turn based RPGs and games with plenty of party members, or just if you miss the Earthbound style of universe, CoE is pretty much for you. Mind the bugs!