Very good
Very good art, animation, sound, VA, interactivity- everything.
I am particularly impressed with the selection of subtitles and the art detail.
-cracks in the walls, shading, shadow, blinking, that sort of thing
There are details that could be improved, but its all there in a good story so far.
Since you have chosen to go for realism rather than cartoony style, I will give you a detailed review including the subtleties that someone at this very high level might use:
The title is not very exciting and the name Grim Island is not too hot. I can't picture anywhere the US would have fought the Germans with an english name. It would look better in capitals anyway.
Generally, the animation is very good, but it could still step up in realism to the highest level. For example, the soldiers marching have a good walk movement- better than anything I can do- but don't move up and down enough, so they look like they are doing the MJ Moonwalk.
Some of the angles seem a bit off- its subtle and its difficult, but the direction people seem to be looking, for example and the angle of flight of the aeroplane. The eyeline of the sniper doesn't look right. If he is looking down the 'scope the pupil needs to shift closer to the centre- and one or two other angles I can't quite put my finger on.
The action somehow doesn't seem as realistic as it might at some points- I suggest that the sniper would have been guided and escorted to the point where he shoots and he would have rested the gun for the critical shot. Generally, the movement in a battle zone is more crouching and keeping down than is suggested through most of this.
I think the scene with the man dragging himself along was put in rather gratuitously- it is not realistic. If you lose the bottom half of your body you cannot drag yourself quite energetically along, the blood will pour out in a few seconds and you lose consciousness. It spoilt the realism of the otherwise good scene.
I am not too sure about the order of the scenes. The way you have it, it looks rather as if the captive is shot, then the US march in and attack and shoot, whilst the prisoner and interrogator are in suspended animation for a few hours.
I hope the sequal will make sense of the final statement. It sounds as if he is saying that the enemy is all around the US troops but the enemy won't escape.
This is all very subtle stuff; this is a very good movie and it will do very well. I look forward to the next instalment.