Neoslavonic is a new constructed language, or conlang. These languages have a history of not being very successful for some odd reason, but they are definitely a good idea. For instance, in Esperanto it takes about 1 year to get to a fluency level that it takes one 8 years to get to in English.
Neoslavonic was created from mixing together the major Slavic languages, presumably Russian, Ukrainian, Belorussian, Bulgarian, Czech, Slovak, Polish, Slovenian, Serbo-Croatian and Macedonian. These languages are fairly similar anyway and there is a fair amount of intelligibility between them. The notion of a Pan-Slavic language is a good idea.
The website is very well done and there seems to be some time and money behind it. Seems to be run out Czechoslovakia.