These are just examples. Feel free to have your students use any materials they think they could use. They can even use recyclable materials like bottle caps for game pieces. Another great resource is talking with your school's art teacher(s).
Access to internet so students can research topics on water pollution
Paper (printer, construction, cardstock, etc.)
Writing utlencils (pens, pencils, markers, crayons, etc.)
Paints and paint brushes
Old game pieces (go to yard sales, thrift shops, etc.)
Spinners
Dice (various sided)
Stickers
Buttons
Etc.
Have your students do a community service project while seeing where your students' understanding of water pollution.
The summative assessment will ultimately be the students' Game Jam Projects. If you want to challenge students you can also have them respond to a short prompt that shows what they learned about water pollution.
Example Question: How can we reduce the human impacts on water pollution.