I do it because we were getting a bunch of messages from our contact form that contained hyperlinks and of course they were all SPAM.
Did you even try this plugin in explicit mode? I mean, up to now more than 2000 websites are using it without a single breakthrough having been reported.
The point is, that a word filter doesn’t make any sense, as the plugin is based upon a proof-of-work approach. This approach is aiming on the business model of a spam bot: Bots usually don’t take the effort to calculate the PoW-puzzle as they spam as many sites in a certain period of time as possible. In contrast to more simple approaches such as filters, honeypots, IP-blocker, behaviour-tracker and alike, this technique is blocking bruteforce-attacks from botnets effectively.
I don’t mean it is impossible to break through. But this makes only sense if an attack is assigning your site dedicatedly, i.e. if it is economically reasonable to take the calculation effort. This is for the most sites outa there is very unlikely. And even then it is easy to just raise the required calculation effort.
I wonder is, what is your intention to ask in this forum, when you have developed a plugin to stop spam on your own?
Cheers, Matthias