Chart re-implemented and added coveralls and other instructions, which will probably not work at all.

app/Support/Steam.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace FireflyIII\Support;
+
+use Carbon\Carbon;
+use FireflyIII\Models\Account;
+
+/**
+ * Class Steam
+ *
+ * @package FireflyIII\Support
+ */
+class Steam
+{
+    /**
+     *
+     * @param Account $account
+     * @param Carbon   $date
+     *
+     * @return float
+     */
+    public function balance(Account $account, Carbon $date = null)
+    {
+        $date    = is_null($date) ? Carbon::now() : $date;
+        $balance = floatval(
+            $account->transactions()->leftJoin(
+                'transaction_journals', 'transaction_journals.id', '=', 'transactions.transaction_journal_id'
+            )->where('transaction_journals.date', '<=', $date->format('Y-m-d'))->sum('transactions.amount')
+        );
+
+        return $balance;
+    }
+
+}