You can use the Dev Zone (ThingWorx Developer Zone | ThingWorx) in order to experience with Thingworx. You will have some restrictions but you can still use the Thingworx Platform.
The Dev Zone, indicates the use of Device Quickstart kits, which are Raspberry Pi, Intel Galileo, Intel Edison to experience Thingworx. But how about other kits from other vendors. Example an IoT capable electronic kit from Texas Instruments. These are TI CC3200 Launchpad and Tiva Launchpad + CC3100 WiFi. Is it possible to experience Thingworx with these electronic kits. The Thingworx website does not have a clear path of documentation how to do this. See, this project below which I have sent sensor data to SaaS Exosite Dashboard. I just accomplished that with documentation and C API's from Exosite.
I am trying to do the same with Thingworx. Also regarding C SDK, I am unable to get that because it is only available for Thingworx partners. I assume it is not possible for me to install Thingworx to my PC either. I can't find at Thingworx website where to download it.