Adding custom tweens

The game comes with Recoil, Poke, SwingCW, and Swing CCW. Id like to add custom ones.
Is it possible to add custom tweens?

With image yes,but with items or scripts no,and map have custom yes,go to Menu>Settings>Map.And u see,and in item u need upload,but need in your gallery or dowload,but need be a image.

u can use piskel to make a animation click export and then click the png download option look where u see collumns and rows that will show you how many collumns u will need to make the animation then go to create a unit click which u want (Top-Down Unit or Sidescroller Unit) and then upload image it will say Collumns And Rows right above the generated link from the image you just uploaded type in as many collumns and rows as u they say in piskel and then go to general inside of unit editor click default animation or add a animation once u set name click the plus sign and then start adding frames 1 by 1 and now your all set