Thanks for the question. It highlights a problem that is at the heart of our modern consumerist society.
The aim of mcuh of our society is to gather wealth because of what it can do for us. Wealth can give us power, significance and security. It allows us to gather possessions to enjoy or experience all that life has to offer. We build wealth because of what it can give us now, here on earth.
Jesus challenges this perspective in Matthew 6:19 by getting us to see a bigger perspective. He is not against wealth, he is not suggesting that people give up their wealth and become poor. Rather he want us to see what wealth is and what it does to us.
Our treasures (whether they be money, possesions or the experiences we have) are not as good as they seem to be. They are transitory. Money loses its value or can be stolen. Possessions wear out, break down or get stolen. And experiences fade. Ultimately when we die we lose it all!!!
As an alternative, Jesus points out that ‘treasure in heaven’ is not like treasure on earth. It does not wear out, it cannot be stolen, it does not fade. Once you have it, you have it for ever - even death cannot take it away.
So what are these treasures in heaven? Well in this passge Jesus does not go into much detail but the rest of the new testament paints a wonderful picture of what it is like.
Treasures in heaven are not so much about having things as about having great relationships. Heaven is the place where we will live with God our creator forever in a renewed relationship - enjoying all the benefits of his goodness, kindness and love. It is the place wher we will have perfect relationships with each other. It is the place where there is no more loneliness, no more tears, no more suffering, no more hatred. It is all the good things of this life without any of the bad things - only much much better.
The problem though is that we can’t have both - this is what Jesus is saying. If we pursue one it will be at the expense of the other because what we put our effort into becomes our focus and heart’s desire. It is where our heart is.
That is not to say that we cannot or should not be wealthy or seek to be wise with the way we use money. But we should not be our focus and aim in life. Where this comes out is in the decisions we make. A person who is focused on ‘treasures on earth’ will decide to work on the weekend rather than go to church or meet for a bible study or pray with their family - it will be seen as more important. A person who is focused on treasures in heaven will decide not to take a promotion because the extra pressure will affect their time they can spend with other christians and so on.
So in answer to your question, yes you can buy your video games so long as the collecting and playing of video games is not getting in the way of your pursuit of heavenly treasures.
If you want to know how to ‘store up treasures for yourself in heaven’ then you can start by looking at “God Makes Sense” to get an idea about what a christian is and then read a letter from the new testament like Colossians.