We've covered Mega Man Maker a couple times before, but it's worth a renewed mention now on account of the multitude of updates it's received since launch, with its largest - Version 1.3 - being major enough to be worth a shiny new trailer. Plus, it's something fun and free to leave you lot with over the weekend.
If you've never played before, then you're in for a treat, assuming you like NES-era platformers in the slightest. Inspired heavily by Nintendo's Mario Maker, Mega Man Maker is an online, fan-made Mega Man construction kit, allowing you to create your own levels, share them with the world, and inflict your terrible spike-laden ideas upon poor, unsuspecting strangers.
This latest iteration adds two new playable characters - Proto Man and Bass - each with their own unique playstyles. Proto Man has a shield which can deflect enemy fire while jumping, while Bass can shoot diagonally and dash-jump very long distances horizontally, making him a more powerful character in many regards. Expect levels designed around Bass in particular to be somewhat more demanding in their platforming.
Four more bosses and 16 enemies also join the roster, along with 6 weapons, 5 'map gimmicks' (environmental quirks often inspired by a particular boss) and a bunch of new tilesets and backgrounds. In short, there's a lot of new playing pieces here, meaning that there's even more ways to make a borderline-unplayable level, but I trust in you all to show restraint.
Mega Man maker does have its limitations, of course. In order to make levels accessible and shareable, they all need to fit into a simple and limited file format, meaning that what you get here isn't nearly as powerful as raw Game Maker-powered engine that it's based on. Thankfully, more ambitious builders can grab the full-fat version alongside much more anarchic dev-jam Make A Good Mega Man Level 2 here, (which Abby covered in great detail here) but you will need some Game Maker experience to get the most out of it.
Mega Man Maker is freeware, fan-made and non-profit, and you can grab it here.