I think the incompatibility warning should be concise so it can be read quickly, maybe give some information about the version running and the version required, and if possible use something other than sleep to keep the message there for a duration, because sleeping makes it feel like it's frozen, and that never feels good. :D
I'm not sure what it should be. Maybe something like this?
This was made for LÖVE 0.8.0
The version running is LÖVE 0.9.0
There may be problems.