A meta search engine I wrote because I was unhappy with the enormity of searx. My instance is hosted here, although I would ask that you host your own instead of actively using mine.
A default configuration is given in config.go.def.
Simply copy this into config.go, which is ignored by git, and make whatever changes you desire.
This file also contains the custom listen and serve command. If you would like to serve the site in a differ manner, using https instead of http perhaps, change this function.
The other files ending with .def are also meant to be modified.
Simply copy them into a file with the .def suffix removed and make whatever changes desired.
opensearch.xml.def contains a default OpenSearch description.
Modify this with the appropriate information to allow your instance of MetaSearch to be added as a search engine to your browser.
index.html.def and results.html.template.def contain the default html which will be served to the user, modify these to change the look of the site.
The score used to rank search results comes from this paper.