Incredibots 

Incredibots 1, 2, and 3 are Flash-based games using the Box2D physics engine where players build mechanisms to complete levels, or just get creative in a sandbox mode. <Wikipedia>

Originally created by Grubby Games, Incredibots 1 and 2 were put into the Public Domain after the company was purchased by Big Fish Games.  They were developed further by members of the Incredibots community forums ("jayther" and "pokeybit") who added several additional features, then "jayther" began work on a brand new version 3 from scratch, which unfortunately was never completed.

With the demise of Flash Player the online versions of Incredibots hosted at the website no longer work, but there are several alternative ways to continue playing the games...

 

Running Incredibots (IB) as a Portable Executable on your PC
Years ago I made Portable Executable versions from the .SWF files for IB1 and IB2 "jaybit" editions.  I couldn't convert IB3 as it doesn't exist anywhere as a single self-contained .SWF file. 
Links below:

Incredibots 1.21

Incredibots 2.33

Download your version of choice, unpack the .ZIP file wherever you want it, and then run it. 

Or, if you don't trust downloads from me (quite right, why should you?) you can do this for yourself...

 

Run IB1 or IB2 on your PC using Adobe's Flash Player Projector (FPP)
Projector lets you run any self-contained .SWF file with no need for a Web Browser or the installation of any Flash Plugins.  You just run the Projector executable, click "File" menu, click "Open", browse to your .SWF file and "Open" it.   You will need:

 

Make your very own all-in-one Portable Executable version of IB1 or IB2
If you have Flash Player Projector (FPP) Version 10 you can use it's "Create Projector" feature to  make your own Portable Executable version of any self-contained .SWF file.
It has to be Version 10 as earlier versions won't properly support IB, and all the later versions of FPP have this feature disabled.

Using FPP 10, open your .SWF file, then on the FPP File menu click "Create Projector" and save it as a new file.  This file is a copy of the FPP with your .SWF permanently embedded inside it. 
You will need:

 

What about Incredibots 3?
This version of Incredibots was entirely created by "jayther" but never completed.  As a result it's been left in a prototype state and is composed of many files scattered across 3 different web domains.  The various distributed parts expect to find each other out there on the web at those locations, so even if you managed to download them all you'd also need to emulate their original web hosts before they'd work.  However, it is possible to get IB3 running on your PC by using BlueMaxima's Flashpoint...

 

BlueMaxima's Flashpoint
https://bluemaxima.org/flashpoint/
Incredibots 1, 2, AND 3 are all available through "Flashpoint".
It's a framework that runs locally on your computer, and lets you run old web-games based on lots of outdated formats like Flash, Shockwave, Java, etc. without the need for a web browser.
The framework emulates whatever web environment each game was originally designed to expect, which is why it can support Incredibots 3.  There are several download options; "Flashpoint Infinity" is the smallest download at 500Mb, which expands to 2Gb once unpacked.  The "Infinity" download doesn't contain any of the games, the files for each one are downloaded from the online Flashpoint repository on first use, and played from the local copy on your computer from then on.

 

Other Alternatives
While there are several web browsers out there that still offer Flash support, some of them come with unwanted malware.  Stay safe, avoid them all.

There are several projects to make alternatives to Adobe's Flash Plugin, ones that would let .SWF content play in modern browsers that no longer support Flash.  Some haven't seen any development in years, some only work on a specific OS, and at least one costs money to use.
Best contender in my opinion is Ruffle which is already being used by the Internet Archive to play some of the Flash content they're preserving.  At this time Ruffle only supports Flash content based on ActionScript 1 and 2.  Incredibots is based on ActionScript 3 which Ruffle doesn't support yet, but may well do in the future.