Nice music and melodies. I think you hit the spot in terms of the emotions.
Arrangement-wise, here are my opinions.
I think the first and second parts feel too disjointed. This mostly has to do with the timbre of the instrument used for the staccato like stabs and the transition. Didn't feel very smooth. You may want to consider writing a bridge section to build up the tempo.
Also, in terms of dynamics, I think the percussion is way too loud. And there is not enough dynamics in the rest of the instrumentation except for the layering of instruments in certain parts.
You may also want to polish the detail part of the music as others have mentioned i.e. the articulations such as sforzando, marcato etc.
In terms of mixing, I feel that the reverb is still over the top. No one uses that much reverb.
Since you are interested in game music specifically, I suggest you go download and listen to the
Dead Space OST by Jason Graves for a good idea of a great sci-fi soundtrack for a game. Listen specifiically
Welcome Aboard the USG Ishimura for a similar but darker sounding arrangement.
The above is purely my opinion and may not be 100% accurate. All in all, you're getting there, just need a bit more.
Also, if you didn't know already, you can study a free orchestration course over at
Northern Sounds.
Good luck.