When using Intel® Data Migration Software, the amount of data on your old storage device must not exceed the size of your new SSD. If the amount of data on your old storage device is greater than the capacity of your Intel® SSD, the data migration will not complete.
If the raw storage space of the source drive is bigger than your new SSD, IDMS will rearrange the partitions and let you migrate the drive as long as the data used does not exceed the size of the target drive.
Since you are using 885 GB in the source drive, you might want to consider the following options:
1. Lower the amount of space used in the source HDD before attempting the clone process with Intel® Data Migration Software. Back up your data to another location and remove it from the HDD, uninstall any applications you don't need to migrate, use the Disk Cleanup tool to free storage space on the HDD.
2. If this does not meet your needs, you might want to check for 3rd party applications that allow cloning the drive, selecting folders or applications for the process.
3. IDMS is designed for full drive cloning, but if you have multiple partitions in your existing drive, you might also find 3rd party tools that allow cloning selected partitions.
Would it be best to just delete Steam, League, Battle.net, etc? And just re download them all?
Please remember that your existing HDD exceeds the size of your SSD by 600+ GB of used space. If you can reduce the amount of space used to a size that will fit in your SSD, then you would be able to clone the drive. Uninstalling any unnecessary software (using Windows® Control Panel - Programs) is one of the options to lower the data stored before a migration, however, if the 885 GB of data are in the same partition, then you will need to free more space to do a migration.
There is also the option to do a clean OS installation in your new SSD, then install any applications or drivers in the new drive. This way you could use you old HDD as a secondary (data) drive, without needing to move or delete your documents or additional files.