Jitter when the camera slides left and right means he should keep it in one spot and offset the screen. I.e., don’t move the camera - move the graphics. Have some X/Y value that gets added to all block positions, that frame. Then any visible gaps between tiles would at least stay put.
The artistic solution to those gaps is to make hidden faces the same color as the top face. Anywhere a cube touches a cube, the sides that meet should not be shaded.
The artistic non-solution is to give each top face an outline so that all looks like a deliberate grid. Like the surface is tiled the way a kitchen is tiled.
An artistic abuse is that blocks could be oriented freely. Any 1x1 pillar of cubes can be stacked funny. Especially if the engine makes non-grid-aligned tiles cheap. Then you could do a ziggurat where every level spirals upward. Admittedly, that would make collision a pain. Even player movement seems to be gridded.